Ensure output arrives on stderr

repo2docker/buildpacks/repo2docker-entrypoint

@@ -15,10 +15,10 @@ if [[ ! -z "${R2D_ENTRYPOINT:-}" ]]; then
     if [[ ! -x "$R2D_ENTRYPOINT" ]]; then
         chmod u+x "$R2D_ENTRYPOINT"
     fi
-    exec "$R2D_ENTRYPOINT" "$@" >&"$log_fd" 2>&1
+    exec "$R2D_ENTRYPOINT" "$@" >&"$log_fd"
 else
-    exec "$@" >&"$log_fd" 2>&1
+    exec "$@" >&"$log_fd"
 fi
 
-# Close the loggging output aggain
-exec {log_fd}>&-
+# Close the logging output again
+#exec {log_fd}>&-

tests/unit/test_env.py

@@ -58,6 +58,10 @@ def test_env():
 
     # all docker output is returned by repo2docker on stderr
     # extract just the declare for better failure message formatting
+    # stdout should be empty
+    assert not result.stdout
+
+    # stderr should contain lines of output
     declares = [x for x in result.stderr.split("\n") if x.startswith("declare")]
     assert 'declare -x FOO="{}"'.format(ts) in declares
     assert 'declare -x BAR="baz"' in declares