refactor: manually add transitions to f-strings

docs/source/conf.py

@@ -61,12 +61,10 @@ from repo2docker.buildpacks.conda import CondaBuildPack
 
 default_python = CondaBuildPack.major_pythons["3"]
 
-rst_prolog = """
+rst_prolog = f"""
 .. |default_python| replace:: **Python {default_python}**
 .. |default_python_version| replace:: {default_python}
-""".format(
+"""
-    default_python=default_python
-)
 
 
 # -- Options for HTML output -------------------------------------------------

repo2docker/__main__.py

@@ -304,8 +304,8 @@ def make_r2d(argv=None):
             r2d.volumes[os.path.abspath(args.repo)] = "."
         else:
             r2d.log.error(
-                'Cannot mount "{}" in editable mode '
+                f'Cannot mount "{args.repo}" in editable mode '
-                "as it is not a directory".format(args.repo),
+                "as it is not a directory",
                 extra=dict(phase=R2dState.FAILED),
             )
             sys.exit(1)

repo2docker/_version.py

@@ -293,7 +293,7 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
         mo = re.search(r"^(.+)-(\d+)-g([0-9a-f]+)$", git_describe)
         if not mo:
             # unparseable. Maybe git-describe is misbehaving?
-            pieces["error"] = "unable to parse git-describe output: '%s'" % describe_out
+            pieces["error"] = f"unable to parse git-describe output: '{describe_out}'"
             return pieces
 
         # tag
@@ -302,10 +302,9 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
             if verbose:
                 fmt = "tag '%s' doesn't start with prefix '%s'"
                 print(fmt % (full_tag, tag_prefix))
-            pieces["error"] = "tag '{}' doesn't start with prefix '{}'".format(
+            pieces[
-                full_tag,
+                "error"
-                tag_prefix,
+            ] = f"tag '{full_tag}' doesn't start with prefix '{tag_prefix}'"
-            )
             return pieces
         pieces["closest-tag"] = full_tag[len(tag_prefix) :]
 

repo2docker/app.py

@@ -425,9 +425,7 @@ class Repo2Docker(Application):
             entry = engines[self.engine]
         except KeyError:
             raise ContainerEngineException(
-                "Container engine '{}' not found. Available engines: {}".format(
+                f"Container engine '{self.engine}' not found. Available engines: {','.join(engines.keys())}"
-                    self.engine, ",".join(engines.keys())
-                )
             )
         engine_class = entry.load()
         return engine_class(parent=self)
@@ -447,16 +445,11 @@ class Repo2Docker(Application):
             spec = cp.detect(url, ref=ref)
             if spec is not None:
                 picked_content_provider = cp
-                self.log.info(
+                self.log.info(f"Picked {cp.__class__.__name__} content provider.\n")
-                    "Picked {cp} content "
-                    "provider.\n".format(cp=cp.__class__.__name__)
-                )
                 break
 
         if picked_content_provider is None:
-            self.log.error(
+            self.log.error(f"No matching content provider found for {url}.")
-                "No matching content provider found for " "{url}.".format(url=url)
-            )
 
         swh_token = self.config.get("swh_token", self.swh_token)
         if swh_token and isinstance(picked_content_provider, contentproviders.Swhid):
@@ -488,8 +481,7 @@ class Repo2Docker(Application):
         Avoids non-JSON output on errors when using --json-logs
         """
         self.log.error(
-            "Error during build: %s",
+            f"Error during build: {evalue}",
-            evalue,
             exc_info=(etype, evalue, traceback),
             extra=dict(phase=R2dState.FAILED),
         )
@@ -619,11 +611,9 @@ class Repo2Docker(Application):
             run_cmd = [
                 "jupyter",
                 "notebook",
-                "--ip",
+                "--ip=0.0.0.0",
-                "0.0.0.0",
+                f"--port={container_port}",
-                "--port",
+                f"--NotebookApp.custom_display_url=http://{host_name}:{host_port}",
-                container_port,
-                f"--NotebookApp.custom_display_url=http://{host_name}:{host_port}"
                 "--NotebookApp.default_url=/lab",
             ]
         else:
@@ -730,7 +720,7 @@ class Repo2Docker(Application):
             try:
                 docker_client = self.get_engine()
             except ContainerEngineException as e:
-                self.log.error("\nContainer engine initialization error: %s\n", e)
+                self.log.error(f"\nContainer engine initialization error: {e}\n")
                 self.exit(1)
 
         # If the source to be executed is a directory, continue using the
@@ -751,8 +741,7 @@ class Repo2Docker(Application):
 
             if self.find_image():
                 self.log.info(
-                    "Reusing existing image ({}), not "
+                    f"Reusing existing image ({self.output_image_spec}), not building."
-                    "building.".format(self.output_image_spec)
                 )
                 # no need to build, so skip to the end by `return`ing here
                 # this will still execute the finally clause and let's us
@@ -763,8 +752,7 @@ class Repo2Docker(Application):
                 checkout_path = os.path.join(checkout_path, self.subdir)
                 if not os.path.isdir(checkout_path):
                     self.log.error(
-                        "Subdirectory %s does not exist",
+                        f"Subdirectory {self.subdir} does not exist",
-                        self.subdir,
                         extra=dict(phase=R2dState.FAILED),
                     )
                     raise FileNotFoundError(f"Could not find {checkout_path}")
@@ -808,8 +796,7 @@ class Repo2Docker(Application):
                         )
 
                     self.log.info(
-                        "Using %s builder\n",
+                        f"Using {bp.__class__.__name__} builder\n",
-                        bp.__class__.__name__,
                         extra=dict(phase=R2dState.BUILDING),
                     )
 

repo2docker/buildpacks/_r_base.py

@@ -26,7 +26,7 @@ def rstudio_base_scripts(r_version):
             # we should have --no-install-recommends on all our apt-get install commands,
             # but here it's important because these recommend r-base,
             # which will upgrade the installed version of R, undoing our pinned version
-            r"""
+            rf"""
             curl --silent --location --fail {rstudio_url} > /tmp/rstudio.deb && \
             curl --silent --location --fail {shiny_server_url} > /tmp/shiny.deb && \
             echo '{rstudio_sha256sum} /tmp/rstudio.deb' | sha256sum -c - && \
@@ -37,24 +37,16 @@ def rstudio_base_scripts(r_version):
             apt-get -qq purge && \
             apt-get -qq clean && \
             rm -rf /var/lib/apt/lists/*
-            """.format(
+            """,
-                rstudio_url=rstudio_url,
-                rstudio_sha256sum=rstudio_sha256sum,
-                shiny_server_url=shiny_server_url,
-                shiny_sha256sum=shiny_sha256sum,
-            ),
         ),
         (
             "${NB_USER}",
             # Install jupyter-rsession-proxy
-            r"""
+            rf"""
                 pip install --no-cache \
                     jupyter-rsession-proxy=={rsession_proxy_version} \
                     jupyter-shiny-proxy=={shiny_proxy_version}
-                """.format(
+                """,
-                rsession_proxy_version=rsession_proxy_version,
-                shiny_proxy_version=shiny_proxy_version,
-            ),
         ),
         (
             # Not all of these locations are configurable; so we make sure

repo2docker/buildpacks/base.py

@@ -594,8 +594,8 @@ class BuildPack:
         # buildpacks/docker.py where it is duplicated
         if not isinstance(memory_limit, int):
             raise ValueError(
-                "The memory limit has to be specified as an"
+                "The memory limit has to be specified as an "
-                "integer but is '{}'".format(type(memory_limit))
+                f"integer but is '{type(memory_limit)}'"
             )
         limits = {}
         if memory_limit:
@@ -647,8 +647,7 @@ class BaseImage(BuildPack):
                     # FIXME: Add support for specifying version numbers
                     if not re.match(r"^[a-z0-9.+-]+", package):
                         raise ValueError(
-                            "Found invalid package name {} in "
+                            f"Found invalid package name {package} in apt.txt"
-                            "apt.txt".format(package)
                         )
                     extra_apt_packages.append(package)
 

repo2docker/buildpacks/conda/__init__.py

@@ -341,15 +341,13 @@ class CondaBuildPack(BaseImage):
             scripts.append(
                 (
                     "${NB_USER}",
-                    r"""
+                    rf"""
                 TIMEFORMAT='time: %3R' \
-                bash -c 'time ${{MAMBA_EXE}} env update -p {0} --file "{1}" && \
+                bash -c 'time ${{MAMBA_EXE}} env update -p {env_prefix} --file "{environment_yml}" && \
                 time ${{MAMBA_EXE}} clean --all -f -y && \
-                ${{MAMBA_EXE}} list -p {0} \
+                ${{MAMBA_EXE}} list -p {env_prefix} \
                 '
-                """.format(
+                """,
-                        env_prefix, environment_yml
-                    ),
                 )
             )
 
@@ -361,36 +359,30 @@ class CondaBuildPack(BaseImage):
             scripts.append(
                 (
                     "${NB_USER}",
-                    r"""
+                    rf"""
-                ${{MAMBA_EXE}} install -p {0} r-base{1} r-irkernel r-devtools -y && \
+                ${{MAMBA_EXE}} install -p {env_prefix} r-base{r_pin} r-irkernel r-devtools -y && \
                 ${{MAMBA_EXE}} clean --all -f -y && \
-                ${{MAMBA_EXE}} list -p {0}
+                ${{MAMBA_EXE}} list -p {env_prefix}
-                """.format(
+                """,
-                        env_prefix, r_pin
-                    ),
                 )
             )
             scripts += rstudio_base_scripts(self.r_version)
             scripts += [
                 (
                     "root",
-                    r"""
+                    rf"""
                     echo auth-none=1 >> /etc/rstudio/rserver.conf && \
                     echo auth-minimum-user-id=0 >> /etc/rstudio/rserver.conf && \
-                    echo "rsession-which-r={}/bin/R" >> /etc/rstudio/rserver.conf && \
+                    echo "rsession-which-r={env_prefix}/bin/R" >> /etc/rstudio/rserver.conf && \
                     echo www-frame-origin=same >> /etc/rstudio/rserver.conf
-                    """.format(
+                    """,
-                        env_prefix
-                    ),
                 ),
                 (
                     "${NB_USER}",
                     # Register the jupyter kernel
-                    r"""
+                    rf"""
-                 R --quiet -e "IRkernel::installspec(prefix='{}')"
+                 R --quiet -e "IRkernel::installspec(prefix='{env_prefix}')"
-                 """.format(
+                 """,
-                        env_prefix
-                    ),
                 ),
             ]
         return scripts

repo2docker/buildpacks/docker.py

@@ -34,8 +34,8 @@ class DockerBuildPack(BuildPack):
         # buildpacks/base.py where it is duplicated
         if not isinstance(memory_limit, int):
             raise ValueError(
-                "The memory limit has to be specified as an"
+                "The memory limit has to be specified as an "
-                "integer but is '{}'".format(type(memory_limit))
+                f"integer but is '{type(memory_limit)}'"
             )
         limits = {}
         if memory_limit:

repo2docker/buildpacks/nix/__init__.py

@@ -62,13 +62,11 @@ class NixBuildPack(BaseImage):
         return super().get_assemble_scripts() + [
             (
                 "${NB_USER}",
-                """
+                f"""
             nix-channel --add https://nixos.org/channels/nixpkgs-unstable nixpkgs && \
             nix-channel --update && \
-            nix-shell {}
+            nix-shell {self.binder_path("default.nix")}
-            """.format(
+            """,
-                    self.binder_path("default.nix")
-                ),
             )
         ]
 

repo2docker/buildpacks/pipfile/__init__.py

@@ -123,9 +123,7 @@ class PipfileBuildPack(CondaBuildPack):
                 assemble_scripts.append(
                     (
                         "${NB_USER}",
-                        '${{NB_PYTHON_PREFIX}}/bin/pip install --no-cache-dir -r "{}"'.format(
+                        f'${{NB_PYTHON_PREFIX}}/bin/pip install --no-cache-dir -r "{nb_requirements_file}"',
-                            nb_requirements_file
-                        ),
                     )
                 )
 

repo2docker/buildpacks/python/__init__.py

@@ -55,9 +55,7 @@ class PythonBuildPack(CondaBuildPack):
                         "${NB_USER}",
                         # want the $NB_PYHTON_PREFIX environment variable, not for
                         # Python's string formatting to try and replace this
-                        '${{NB_PYTHON_PREFIX}}/bin/pip install --no-cache-dir -r "{}"'.format(
+                        f'${{NB_PYTHON_PREFIX}}/bin/pip install --no-cache-dir -r "{nb_requirements_file}"',
-                            nb_requirements_file
-                        ),
                     )
                 )
 

repo2docker/buildpacks/r.py

@@ -336,12 +336,10 @@ class RBuildPack(PythonBuildPack):
             (
                 "${NB_USER}",
                 # Install a pinned version of devtools, IRKernel and shiny
-                r"""
+                rf"""
-                R --quiet -e "install.packages(c('devtools', 'IRkernel', 'shiny'), repos='{devtools_cran_mirror_url}')" && \
+                R --quiet -e "install.packages(c('devtools', 'IRkernel', 'shiny'), repos='{self.get_devtools_snapshot_url()}')" && \
                 R --quiet -e "IRkernel::installspec(prefix='$NB_PYTHON_PREFIX')"
-                """.format(
+                """,
-                    devtools_cran_mirror_url=self.get_devtools_snapshot_url()
-                ),
             ),
         ]
 
@@ -374,8 +372,7 @@ class RBuildPack(PythonBuildPack):
                     "${NB_USER}",
                     # Delete /tmp/downloaded_packages only if install.R fails, as the second
                     # invocation of install.R might be able to reuse them
-                    "Rscript %s && touch /tmp/.preassembled || true && rm -rf /tmp/downloaded_packages"
+                    f"Rscript {installR_path} && touch /tmp/.preassembled || true && rm -rf /tmp/downloaded_packages",
-                    % installR_path,
                 )
             ]
 
@@ -392,9 +389,7 @@ class RBuildPack(PythonBuildPack):
                     "${NB_USER}",
                     # only run install.R if the pre-assembly failed
                     # Delete any downloaded packages in /tmp, as they aren't reused by R
-                    """if [ ! -f /tmp/.preassembled ]; then Rscript {}; rm -rf /tmp/downloaded_packages; fi""".format(
+                    f"""if [ ! -f /tmp/.preassembled ]; then Rscript {installR_path}; rm -rf /tmp/downloaded_packages; fi""",
-                        installR_path
-                    ),
                 )
             ]
 

repo2docker/contentproviders/base.py

@@ -68,6 +68,6 @@ class Local(ContentProvider):
 
     def fetch(self, spec, output_dir, yield_output=False):
         # nothing to be done if your content is already in the output directory
-        msg = "Local content provider assumes {} == {}".format(spec["path"], output_dir)
+        msg = f'Local content provider assumes {spec["path"]} == {output_dir}'
         assert output_dir == spec["path"], msg
-        yield "Using local repo {}.\n".format(spec["path"])
+        yield f'Using local repo {spec["path"]}.\n'

repo2docker/contentproviders/dataverse.py

@@ -76,9 +76,7 @@ class Dataverse(DoiProvider):
             data = self.urlopen(search_url).json()["data"]
             if data["count_in_response"] != 1:
                 self.log.debug(
-                    "Dataverse search query failed!\n - doi: {}\n - url: {}\n - resp: {}\n".format(
+                    f"Dataverse search query failed!\n - doi: {doi}\n - url: {url}\n - resp: {json.dump(data)}\n"
-                        doi, url, json.dump(data)
-                    )
                 )
                 return
 
@@ -98,16 +96,14 @@ class Dataverse(DoiProvider):
         host = spec["host"]
 
         yield f"Fetching Dataverse record {record_id}.\n"
-        url = "{}/api/datasets/:persistentId?persistentId={}".format(
+        url = f'{host["url"]}/api/datasets/:persistentId?persistentId={record_id}'
-            host["url"], record_id
-        )
 
         resp = self.urlopen(url, headers={"accept": "application/json"})
         record = resp.json()["data"]
 
         for fobj in deep_get(record, "latestVersion.files"):
-            file_url = "{}/api/access/datafile/{}".format(
+            file_url = (
-                host["url"], deep_get(fobj, "dataFile.id")
+                f'{host["url"]}/api/access/datafile/{deep_get(fobj, "dataFile.id")}'
             )
             filename = os.path.join(fobj.get("directoryLabel", ""), fobj["label"])
 

repo2docker/contentproviders/figshare.py

@@ -75,11 +75,9 @@ class Figshare(DoiProvider):
         article_version = spec["version"]
         host = spec["host"]
 
-        yield "Fetching Figshare article {} in version {}.\n".format(
+        yield f"Fetching Figshare article {article_id} in version {article_version}.\n"
-            article_id, article_version
-        )
         resp = self.urlopen(
-            "{}{}/versions/{}".format(host["api"], article_id, article_version),
+            f'{host["api"]}{article_id}/versions/{article_version}',
             headers={"accept": "application/json"},
         )
 

repo2docker/contentproviders/git.py

@@ -43,7 +43,7 @@ class Git(ContentProvider):
             hash = check_ref(ref, output_dir)
             if hash is None:
                 self.log.error(
-                    "Failed to check out ref %s", ref, extra=dict(phase=R2dState.FAILED)
+                    f"Failed to check out ref {ref}", extra=dict(phase=R2dState.FAILED)
                 )
                 if ref == "master":
                     msg = (

repo2docker/contentproviders/hydroshare.py

@@ -59,7 +59,7 @@ class Hydroshare(DoiProvider):
         resource_id = spec["resource"]
         host = spec["host"]
 
-        bag_url = "{}{}".format(host["django_irods"], resource_id)
+        bag_url = f'{host["django_irods"]}{resource_id}'
 
         yield f"Downloading {bag_url}.\n"
 
@@ -76,9 +76,7 @@ class Hydroshare(DoiProvider):
                 msg = "Bag taking too long to prepare, exiting now, try again later."
                 yield msg
                 raise ContentProviderException(msg)
-            yield "Bag is being prepared, requesting again in {} seconds.\n".format(
+            yield f"Bag is being prepared, requesting again in {wait_time} seconds.\n"
-                wait_time
-            )
             time.sleep(wait_time)
             conn = self.urlopen(bag_url)
         if conn.status_code != 200:

repo2docker/contentproviders/mercurial.py

@@ -60,7 +60,7 @@ class Mercurial(ContentProvider):
                 )
             except subprocess.CalledProcessError:
                 self.log.error(
-                    "Failed to update to ref %s", ref, extra=dict(phase=R2dState.FAILED)
+                    f"Failed to update to ref {ref}", extra=dict(phase=R2dState.FAILED)
                 )
                 raise ValueError(f"Failed to update to ref {ref}")
 

repo2docker/contentproviders/zenodo.py

@@ -68,7 +68,7 @@ class Zenodo(DoiProvider):
 
         yield f"Fetching Zenodo record {record_id}.\n"
         resp = self.urlopen(
-            "{}{}".format(host["api"], record_id),
+            f'{host["api"]}{record_id}',
             headers={"accept": "application/json"},
         )
 

repo2docker/utils.py

@@ -136,13 +136,10 @@ def validate_and_generate_port_mapping(port_mappings):
         try:
             p = int(port)
         except ValueError as e:
-            raise ValueError(
+            raise ValueError(f'Port specification "{mapping}" has an invalid port.')
-                'Port specification "{}" has ' "an invalid port.".format(mapping)
-            )
         if not 0 < p <= 65535:
             raise ValueError(
-                'Port specification "{}" specifies '
+                f'Port specification "{mapping}" specifies a port outside 1-65535.'
-                "a port outside 1-65535.".format(mapping)
             )
         return port
 
@@ -152,8 +149,7 @@ def validate_and_generate_port_mapping(port_mappings):
             port, protocol = parts
             if protocol not in ("tcp", "udp"):
                 raise ValueError(
-                    'Port specification "{}" has '
+                    f'Port specification "{mapping}" has an invalid protocol.'
-                    "an invalid protocol.".format(mapping)
                 )
         elif len(parts) == 1:
             port = parts[0]
@@ -310,14 +306,14 @@ class ByteSpecification(Integer):
             num = float(value[:-1])
         except ValueError:
             raise TraitError(
-                "{val} is not a valid memory specification. "
+                f"{value} is not a valid memory specification. "
-                "Must be an int or a string with suffix K, M, G, T".format(val=value)
+                "Must be an int or a string with suffix K, M, G, T"
             )
         suffix = value[-1]
         if suffix not in self.UNIT_SUFFIXES:
             raise TraitError(
-                "{val} is not a valid memory specification. "
+                f"{value} is not a valid memory specification. "
-                "Must be an int or a string with suffix K, M, G, T".format(val=value)
+                "Must be an int or a string with suffix K, M, G, T"
             )
         else:
             return int(float(num) * self.UNIT_SUFFIXES[suffix])

tests/conda/py2/verify

@@ -30,4 +30,4 @@ for pkg in pkgs:
         assert pkg["version"].startswith("2.7.")
         break
 else:
-    assert False, "python not found in %s" % pkg_names
+    assert False, f"python not found in {pkg_names}"

tests/conftest.py

@@ -65,7 +65,7 @@ def make_test_func(args, skip_build=False, extra_run_kwargs=None):
         container = app.start_container()
         port = app.port
         # wait a bit for the container to be ready
-        container_url = "http://localhost:%s/api" % port
+        container_url = f"http://localhost:{port}/api"
         # give the container a chance to start
         time.sleep(1)
         try:
@@ -77,13 +77,13 @@ def make_test_func(args, skip_build=False, extra_run_kwargs=None):
                 try:
                     info = requests.get(container_url).json()
                 except Exception as e:
-                    print("Error: %s" % e)
+                    print(f"Error: {e}")
                     time.sleep(i * 3)
                 else:
                     print(info)
                     success = True
                     break
-            assert success, "Notebook never started in %s" % container
+            assert success, f"Notebook never started in {container}"
         finally:
             # stop the container
             container.stop()
@@ -211,7 +211,7 @@ class Repo2DockerTest(pytest.Function):
     def repr_failure(self, excinfo):
         err = excinfo.value
         if isinstance(err, SystemExit):
-            cmd = "jupyter-repo2docker %s" % " ".join(map(pipes.quote, self.args))
+            cmd = f'jupyter-repo2docker {" ".join(map(pipes.quote, self.args))}'
             return f"{cmd} | exited with status={err.code}"
         else:
             return super().repr_failure(excinfo)

tests/unit/test_connect_url.py

@@ -59,13 +59,13 @@ def test_connect_url(tmpdir):
             try:
                 info = requests.get(container_url).json()
             except Exception as e:
-                print("Error: %s" % e)
+                print(f"Error: {e}")
                 time.sleep(i * 3)
             else:
                 print(info)
                 success = True
                 break
-        assert success, "Notebook never started in %s" % container
+        assert success, f"Notebook never started in {container}"
     finally:
         # stop the container
         container.stop()

tests/unit/test_subdir.py

@@ -21,7 +21,7 @@ def test_subdir(run_repo2docker):
     run_repo2docker(argv)
 
     # check that we restored the current working directory
-    assert cwd == os.getcwd(), "We should be back in %s" % cwd
+    assert cwd == os.getcwd(), f"We should be back in {cwd}"
 
 
 def test_subdir_in_image_name():

tests/unit/test_users.py

@@ -34,19 +34,14 @@ def test_user():
         subprocess.check_call(
             [
                 "repo2docker",
-                "-v",
+                f"--volume={tmpdir}:/home/{username}",
-                f"{tmpdir}:/home/{username}",
+                f"--user-id={userid}",
-                "--user-id",
+                f"--user-name={username}",
-                userid,
-                "--user-name",
-                username,
                 tmpdir,
                 "--",
                 "/bin/bash",
                 "-c",
-                "id -u > id && pwd > pwd && whoami > name && echo -n $USER > env_user".format(
+                "id -u > id && pwd > pwd && whoami > name && echo -n $USER > env_user",
-                    ts
-                ),
             ]
         )
 

tests/venv/usr-bin/verify

@@ -4,4 +4,4 @@ import os
 
 assert os.path.expanduser("~/.local/bin") in os.getenv("PATH"), os.getenv("PATH")
 assert os.getcwd() == os.environ["REPO_DIR"]
-assert "{}/.local/bin".format(os.environ["REPO_DIR"]) in os.getenv("PATH")
+assert f'{os.environ["REPO_DIR"]}/.local/bin' in os.getenv("PATH")

versioneer.py

@@ -1106,7 +1106,7 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
         mo = re.search(r"^(.+)-(\d+)-g([0-9a-f]+)$", git_describe)
         if not mo:
             # unparseable. Maybe git-describe is misbehaving?
-            pieces["error"] = "unable to parse git-describe output: '%s'" % describe_out
+            pieces["error"] = f"unable to parse git-describe output: '{describe_out}'"
             return pieces
 
         # tag
@@ -1115,10 +1115,9 @@ def git_pieces_from_vcs(tag_prefix, root, verbose, run_command=run_command):
             if verbose:
                 fmt = "tag '%s' doesn't start with prefix '%s'"
                 print(fmt % (full_tag, tag_prefix))
-            pieces["error"] = "tag '{}' doesn't start with prefix '{}'".format(
+            pieces[
-                full_tag,
+                "error"
-                tag_prefix,
+            ] = f"tag '{full_tag}' doesn't start with prefix '{tag_prefix}'"
-            )
             return pieces
         pieces["closest-tag"] = full_tag[len(tag_prefix) :]
 
@@ -1256,7 +1255,7 @@ def write_to_version_file(filename, versions):
     with open(filename, "w") as f:
         f.write(SHORT_VERSION_PY % contents)
 
-    print("set {} to '{}'".format(filename, versions["version"]))
+    print(f"set {filename} to '{versions['version']}'")
 
 
 def plus_or_dot(pieces):