Fix the wrong push commits in the pull request when force push

[lunny]

Fix #36905

• Force-push push comments now compute commit IDs via a symmetric range against the base branch, while normal pushes use a linear range; force-
  pushes delete only non-force-push comments and tolerate missing old commits. services/pull/comment.go:17. In a force-push scenario, oldCommitID refers to the commit that existed before the force push, so using it as the start of the range may miss relevant commits or produce incorrect results.
• Introduces gitrepo.GetCommitIDsBetween to centralize commit-range retrieval (supports .. and ...) with unit tests.
  modules/gitrepo/compare.go:46 modules/gitrepo/compare_test.go:44
• Adds Comment.GetPushActionContent for decoding PR push comment payloads to identify force-push entries. models/issues/comment.go:343
• Expands pull comment tests to cover deletion behavior, missing old commit, and base/head branch scenarios. services/pull/comment_test.go:18

[Copilot]

Pull request overview

This PR addresses #36905 by fixing how commit lists are computed for pull request timeline “push” entries after a force-push, ensuring the timeline reflects the full set of commits currently on the PR branch (not just the delta from the previous head).

Changes:

• Update force-push handling in CreatePushPullComment to compute PR commit IDs via merge-base comparison against the base branch.
• Add a new helper (GetCompareCommitIDsWithMergeBase) in services/git plus unit test coverage for it.
• Add a pull service test case intended to cover “missing old commit” scenarios during force-push.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
services/pull/comment.go	Switch force-push commit enumeration to merge-base-based compare logic.
services/pull/comment_test.go	Add a force-push test case targeting missing/unreachable old commit scenarios.
services/git/compare.go	Introduce GetCompareCommitIDsWithMergeBase helper to list commits from merge-base..head.
services/git/compare_test.go	Add unit test validating the helper’s output against CommitsBetweenNotBase.
services/git/main_test.go	Add TestMain bootstrap for services/git tests (unittest DB init).

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[wxiaoguang]

Don't make it depends on "db"

Don't use func TestMain(m *testing.M) { unittest.MainTest(m) }

Why the simple git operation should depend on db?

[silverwind]

In essence the fix should be pretty simple: The commit timeline (and tab count) should always show the actual commits present in the branch, ordered into the timeline with their authoring date. Force-push can rewrite the entire commit timeline, so must invalidate all commits in the timeline.

Could just make it completely git-based and skip storing in the DB entirely, but do whatever perform better, but a DB cache does bring the invalidation complexity.

[silverwind]

Review by Claude on behalf of @silverwind

[Copilot]

Pull request overview

This PR addresses incorrect commit lists shown in pull request timeline “push” comments after a force-push by changing how commit IDs are collected for force-push events.

Changes:

• Update force-push handling to compute commit IDs from the PR base branch to the new head, instead of oldCommitID..newCommitID.
• Add a unit test case intended to cover force-push when the old commit is missing.
• Introduce gitrepo.GetCommitIDsBetween() plus tests for it.

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 4 comments.

File	Description
services/pull/comment.go	Changes force-push commit range calculation to a base-ref → new-head comparison.
services/pull/comment_test.go	Adds a regression-oriented test for missing old commit in force-push.
modules/gitrepo/compare.go	Adds a helper to return commit IDs for a rev-list range.
modules/gitrepo/compare_test.go	Adds tests covering the new rev-list helper.

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