Fix AssertionError when creating a course via the web UI

[polds]

Problem

Creating a course through Set up new course fails with an AssertionError, even though the content validates and the course is actually created. The user sees:

Course content validated, creation succeeded.
Course creation failed: AssertionError:

…and then a 500 when opening the new course.

Traceback:

File "course/versioning.py", line 324, in set_up_new_course
    assert repo is not None
AssertionError

Cause

set_up_new_course initializes a local repo = None and closes it on both the success (else) and failure (except) paths. But git_clone_and_create_course opens its own repo via Repo.init(...) and never returns it, so the caller's repo stays None. On the success path, else: assert repo is not None therefore always fires — after create_course has already validated content and written the Course row. The clone's file handles also leak, since the intended repo.close() never receives a real repo.

Fix

Return the initialized repo from git_clone_and_create_course and assign it in the caller, so the existing close() logic on both branches works as intended. Two-line change plus a return annotation; no behavior change beyond closing the repo as was already intended.

Testing

• python -m py_compile course/versioning.py passes.
• Verified by reasoning through both paths: on success repo is now the real repo and is closed; on failure before the assignment, repo is None and the if repo is not None guard still holds.

[inducer]

Thanks! LGTM, in it goes. Sorry about the delay.