Fix#36483
In git log/rev-list, the "..." syntax represents the symmetric
difference between two references, which is different from the meaning
of "..." in git diff (where it implies diffing from the merge base).
For listing PR commits, we must use `merge-base..head` to include only
the commits introduced by the head branch. Otherwise, commits newly
pushed to the base branch would also be included, which is incorrect.
Maybe fix#32018
- Use `gitrepo.GetMergeBase` method instead of other two
implementations.
- Add `FetchRemoteCommit` so that we don't need to add many `remote` to
the git repository to avoid possible git lock conflicts. A lock will
start when invoke the function, it will be invoked when cross-repository
comparing. The head repository will fetch the base repository's base
commit id. In most situations, it should lock the fork repositories so
that it should not become a bottleneck.
- Improve `GetCompareInfo` to remove unnecessarily adding remote.
- Remove unnecessary parameters of `SignMerge`.
- The compare page head title should be `compare` but not `new pull
request`.
- Use `UnstableGuessRefByShortName` instead of duplicated functions
calls.
- Direct-compare, tags, commits compare will not display `New Pull
Request` button any more.
The new screenshot
<img width="1459" height="391" alt="image"
src="https://github.com/user-attachments/assets/64e9b070-9c0b-41d1-b4b8-233b96270e1b"
/>
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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
