fix(but-graph): don't pin an orphaned target commit after a history rewrite#14556
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ameyypawar wants to merge 1 commit into
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fix(but-graph): don't pin an orphaned target commit after a history rewrite#14556ameyypawar wants to merge 1 commit into
ameyypawar wants to merge 1 commit into
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When a target branch's history is rewritten upstream (e.g. `git filter-repo` or `git filter-branch` followed by a force-push), the stored target commit (`gitbutler.project.targetCommitId`) points at a commit that still exists as an object but shares no history with the rewritten target ref. Workspace graph init pinned it as an integrated tip after only checking that the object existed, so the workspace ended up with no merge-base against its target -- the perpetual "No merge-base found" / "Target branch divergence" state described in the issue. Before pinning a stored target commit, drop it when, on a full clone, it shares no merge-base with the live target-ref tip (a genuine rewrite); the workspace then falls back to the live target tip. On a shallow clone the commit is kept, because gix's merge-base cannot distinguish a below-graft merge-base from a real rewrite, so keeping it is the conservative choice. Adds a regression test for the full-clone orphaned-target case. Fixes gitbutlerapp#14415
ameyypawar
requested review from
Byron,
Caleb-T-Owens,
estib-vega,
jonathantanmy2 and
krlvi
as code owners
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Fixes #14415.
Bug
After an upstream history rewrite (
git filter-repo/git filter-branch+ force-push), GitButler gets stuck in a perpetual "No merge-base found" / "Target branch divergence" state and keeps recreatinggitbutler/workspacefrom the pre-rewrite commit.Cause
The stored target commit (
gitbutler.project.targetCommitId) still exists as an object but is disjoint from the rewritten target ref. Inbut-graph'sinitial_tips_from_workspace_metadata, a storedtarget_commit_idwas pinned as an integrated tip after only checking that the object existed (repo.find_commit) — never that it was still reachable from the target. The orphaned commit got pinned, leaving the workspace with no merge-base against its target. (This matches @shanoor's root-cause analysis in the issue.)Fix
Before pinning a stored target commit, drop it when — on a full clone — it shares no merge-base with the live target-ref tip (a genuine rewrite). The workspace then falls back to the live target tip and the merge-base is restored.
On a shallow clone the commit is kept: gix's merge-base silently treats a below-graft parent as a root, so a below-graft merge-base is indistinguishable from a real rewrite — keeping the stored commit is the conservative choice and matches prior behavior (never dropping a still-reachable target).
Test
Adds
ignores_orphaned_target_commit_unreachable_from_target_ref, which pins a disjoint commit as the target and asserts the workspace resolves to the live target tip instead. Fails onmaster, passes here; the fullbut-graphsuite stays green.