Don't rely on git failing on non-git folders (it may find a repo, lower in the hierarchy, typically while testing).

Author: JulienPalard

build_docs.py

@@ -123,10 +123,12 @@ def git_clone(repository, directory, branch=None):
     """
     logging.info("Updating repository %s in %s", repository, directory)
     try:
+        if not os.path.isdir(os.path.join(directory, '.git')):
+            raise AssertionError("Not a git repository.")
         if branch:
             shell_out(['git', '-C', directory, 'checkout', branch])
         shell_out(['git', '-C', directory, 'pull', '--ff-only'])
-    except subprocess.CalledProcessError:
+    except (subprocess.CalledProcessError, AssertionError):
         if os.path.exists(directory):
             shutil.rmtree(directory)
         logging.info("Cloning %s into %s", repository, directory)