GeezerVison

- Add tests
- [P2] Disable lazy fetching during no-fetch updates — git/objects/submodule/base.py:865-866
  For a partial-cloned submodule (for example, using `--filter=blob:none`), the
  target commit can be cached while its blobs are missing. Skipping `Remote.fetch`
  does not prevent the later checkout/reset from implicitly fetching those blobs.
  I reproduced `update(no_fetch=True)` spawning `git fetch origin ... --stdin`
  despite this guard. This violates the documented local-only behavior. Disable
  Git's lazy fetching for commands executed in this mode, including checkout and
  restoration.
- [P2] Propagate no_fetch to recursive root-module updates — git/objects/submodule/root.py:442-442
  For repositories with nested submodules,
  `Repo.submodule_update(no_fetch=True)` still fetches nested remotes. The flag
  reaches this immediate `sm.update(recursive=False, ...)`, but the subsequent
  `type(self)(sm.module()).update(...)` call omits it and defaults to `False`.
  Since root updates recurse by default, offline updates fail even when all
  required objects are cached. Forward the flag to the recursive call too.

- [P2] Skip the branch-change fetch loop when no_fetch is set — git/objects/submodule/root.py:90-90
  When `.gitmodules` changes a submodule's configured branch, the branch-change
  handler still unconditionally calls `remote.fetch(...)` for every remote.
  Consequently, even `submodule_update(recursive=False, no_fetch=True)` accesses
  remotes and fails offline, including when the target remote-tracking branch
  already exists locally. Guard that fetch loop with this flag as well.

- [P2] Handle URL changes without requiring freshly fetched refs — git/objects/submodule/root.py:282-283
  When a submodule's URL changes with `no_fetch=True`, the newly created
  `__new_origin__` remote has no refs, so the following `smr.refs` branch check
  raises `ValueError`. This occurs even when switching to an identical mirror with
  all required history cached locally, and leaves the temporary remote behind. The
  no-fetch path must handle the fetch-dependent validation and remote replacement,
  not merely skip this fetch.

- [P2] Allow restoring retained repositories without fetching — git/objects/submodule/base.py:893-896
  After `git submodule deinit`, the retained repository under
`.git/modules/<name>` can already contain the requested commit. This branch has
  validated that repository but now rejects `update(init=True, no_fetch=True)`
  merely because its checkout is empty. Reconnecting the repository and restoring
  cached contents requires no network access; native `git submodule update --init
  --no-fetch` succeeds in this case. Allow restoration and conditionally skip the
  later `fetch_remotes(mrepo)` instead.

Assisted-by: GPT 6.0
Co-authored-by: GPT 6.0 <[email protected]>