Revert "Fix Git clone error when checking out reference"

This reverts commit 63cfb5eac0.

app/utils/git.py

@@ -40,13 +40,28 @@ def get_temp_dir():
 # Throws `TaskError` on failure.
 # Caller is responsible for deleting returned directory.
 @contextlib.contextmanager
-def clone_repo(urlstr, ref=None):
+def clone_repo(urlstr, ref=None, recursive=False):
 	gitDir = os.path.join(tempfile.gettempdir(), randomString(10))
 
+	err = None
 	try:
 		gitUrl = generateGitURL(urlstr)
-		repo = git.Repo.clone_from(gitUrl, gitDir, b=ref,
-				progress=None, env=None, depth=1, recursive=True, kill_after_timeout=15)
+		print("Cloning from " + gitUrl)
+
+		if ref is None:
+			repo = git.Repo.clone_from(gitUrl, gitDir,
+					progress=None, env=None, depth=1, recursive=recursive, kill_after_timeout=15)
+		else:
+			assert ref != ""
+
+			repo = git.Repo.init(gitDir)
+			origin = repo.create_remote("origin", url=gitUrl)
+			assert origin.exists()
+			origin.fetch()
+			repo.git.checkout(ref)
+
+			for submodule in repo.submodules:
+				submodule.update(init=True)
 
 		yield repo
 		shutil.rmtree(gitDir)