CI: Speed up compile stage jobs

.gitlab-ci.yml

@@ -33,7 +33,13 @@ make-dist:
     - sane-backends-*.tar.gz
     expire_in: 1 day
 
+# This template is used for all jobs in the compile stage.  As the
+# template solely relies on the source tarball there is no need to
+# checkout the git repository.
+
 .compile_template: &compile_definition
+  variables:
+    GIT_DEPTH: "0"
   stage: compile
   script:
   - mkdir build