Update mergebase in pr checker

[zeripath]

During PR check we should update the merge-base if it changes.

Fix #10502

[lunny]

I think we also need a migration to fix the old PRs.

[codecov-io]

Codecov Report

Merging #10586 into master will increase coverage by 0.01%.
The diff coverage is 0%.

@@            Coverage Diff             @@
##           master   #10586      +/-   ##
==========================================
+ Coverage   43.71%   43.73%   +0.01%     
==========================================
  Files         585      585              
  Lines       82026    82026              
==========================================
+ Hits        35861    35876      +15     
+ Misses      41725    41712      -13     
+ Partials     4440     4438       -2

Impacted Files	Coverage Δ
services/pull/check.go	55.48% <0%> (+5.48%)	⬆️
modules/indexer/stats/queue.go	62.5% <0%> (-18.75%)	⬇️
modules/indexer/stats/db.go	40.62% <0%> (-9.38%)	⬇️
modules/git/utils.go	65.67% <0%> (-4.48%)	⬇️
modules/git/repo.go	46.78% <0%> (-0.92%)	⬇️
services/pull/pull.go	35.88% <0%> (+1.17%)	⬆️
services/pull/temp_repo.go	31.62% <0%> (+2.56%)	⬆️
services/pull/patch.go	64.51% <0%> (+2.58%)	⬆️
modules/git/command.go	89.56% <0%> (+2.6%)	⬆️
modules/process/manager.go	78.31% <0%> (+3.61%)	⬆️
... and 1 more

---

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[zeripath]

Hmm so on restart of Gitea all unmerged PRs should get their mergebase updated.

The issue with merged ones will be that it'll be difficult to decide what it should be after it's merged.

[zeripath]

OK just doing some testing on my system this fix does appear to fix #10502

[guillep2k]

Somehow I was expecting a PR with 17 files and 300+ lines changed. 😅

[6543]

Ping lgtm

[6543]

For migration: do we realy need one or just add this as option to the docktor?

[lunny]

Fixing old merged PR could be another PR.

[jolheiser]

Please send backport. 🙂

[lunny]

migrations/v128.go:79:fixMergeBase() [E] Unable to get merge base for PR ID 4314, Index 6 in ---/---. Error: exit status 128 - fatal: Not a valid object name fix-admin-2-master
& exit status 128 - fatal: ambiguous argument 'refs/heads/fix-admin-2-master': unknown revision or path not in the working tree.
Use '--' to separate paths from revisions, like this:
'git [...] -- [...]'

found some logs from gitea.com

[zeripath]

That means the base branch was deleted - so the merge base is impossible to recalculate. If the pr compare page was broken it will remain broken.

[zeripath]

Interestingly - and concerningly - viewing that PR gives me a 500. That entry will be skipped by the migration - therefore it's not that v128.go has broken this - but rather that we're not handling deleted base branches very well.