fix(core): checkout template repository by revision (#2189)

* fix #2024
* add test for checking out project template with a specified commit sha

Author: vigsterkr

renku/core/commands/init.py

@@ -354,14 +354,14 @@ def fetch_template_from_git(source, ref=None, tempdir=None):
     if ref:
         try:
             # fetch ref and set the HEAD
-            template_repo.remotes.origin.fetch(ref)
+            template_repo.remotes.origin.fetch()
             try:
                 template_repo.head.reset(template_repo.commit(ref))
             except git.exc.BadName:
                 ref = "origin/{0}".format(ref)
                 template_repo.head.reset(template_repo.commit(ref))
             git_repo = git.Git(str(tempdir))
-        except git.exc.GitCommandError as e:
+        except (git.exc.GitCommandError, git.exc.BadName) as e:
             raise errors.GitError("Cannot fetch and checkout reference {0}".format(ref)) from e
     else:
         template_repo.remotes.origin.fetch()

tests/core/commands/test_init.py

@@ -50,6 +50,7 @@ def test_fetch_template_from_git(template):
     # ? REF: https://docs.pytest.org/en/stable/proposals/parametrize_with_fixtures.html
     parametrize = [
         {"url": template["url"], "ref": template["ref"], "error": None},
+        {"url": template["url"], "ref": "817b03c", "error": None},
         {"url": "fake", "ref": template["ref"], "error": errors.GitError},
         {"url": template["url"], "ref": "fake", "error": errors.GitError},
     ]