Can't pull student repos

使用提供的调试输出作为参考，先执行 gh classroom clone student-repos，再执行 gh classroom pull student-repos，重现该故障。首先跟踪 git fetch upstream refs/heads/master 和 git merge-base --is-ancestor 附近的 pull 路径；完成的标志是仓库能够成功更新，并且未发生变化的仓库不再报告存在分歧的更改。

Describe the bug

I cannot pull updates in students assignment using gh classroom pull student-repos -a ... command. It says:

failed to run gh: can't sync because there are diverging changes; use `--force` to overwrite the destination branch
. error: exit status 1

however, there are no diverging changes. It also does not work when there are no updates, as shown here:

$ gh classroom clone student-repos
? Select a classroom: XXXX
? Select an assignment: YYYY
Creating directory:  /ZZZZ-submissions
Cloning into: /ZZZZ-submissions/ZZZ-AAA
Cloning into: /ZZZZ-submissions/ZZZ-BBB
Cloned 2 repos.
 
$ gh classroom pull student-repos
? Select a classroom: XXXX
? Select an assignment: YYYY
Pulling repo: /ZZZZ-submissions/ZZZ-AAA
failed to run gh: can't sync because there are diverging changes; use `--force` to overwrite the destination branch
. error: exit status 1
Pulling repo: /ZZZZ-submissions/ZZZ-BBBB
failed to run gh: can't sync because there are diverging changes; use `--force` to overwrite the destination branch
. error: exit status 1

$ gh --version
gh version 2.52.0 (2024-07-15)
https://github.com/cli/cli/releases/tag/v2.52.0
$ gh extension list
NAME          REPO                 VERSION
gh act        nektos/gh-act        v0.2.55
gh classroom  github/gh-classroom  v0.1.14

Steps to reproduce the behavior

1. Clone students repositories using gh classroom clone ....
2. (Optional) Modify the reference repository and request Pull Request, accept it.
3. Try to pull repository again

Expected vs actual behaviour

I would expect all repositories to be updated. Now I need to update them manually, which works ok (no diverging changes).

Logs

Paste the activity from your command line. Redact if needed.

$GH_DEBUG=true gh classroom pull student-repos -a AAAAAA
* Request at 2024-07-23 13:35:52.177507471 +0200 CEST m=+0.028484741
* Request to https://api.github.com/assignments/AAAAAA
* Request took 414.42728ms
Pulling repo: XXXXXX
failed to run gh: [git remote -v]
[git config --get-regexp ^remote\..*\.gh-resolved$]
[git remote -v]
[git config --get-regexp ^remote\..*\.gh-resolved$]
* Request at 2024-07-23 13:35:52.616066256 +0200 CEST m=+0.020500993
* Request to https://api.github.com/graphql
* Request took 295.087327ms
[git -c credential.helper= -c credential.helper=!"/usr/bin/gh" auth git-credential fetch -q upstream refs/heads/master]
[git rev-parse --verify refs/heads/master]
[git merge-base --is-ancestor master FETCH_HEAD]
can't sync because there are diverging changes; use `--force` to overwrite the destination branch
. error: exit status 1

The command was executed in the same directory where gh classroom clone student-repos --all was executed before.