Closes#1579.
api/updates.py was building the GitHub compare URL from local HEAD short SHA:
repoUrl + '/compare/' + curSha + '...' + newSha
where curSha = `git rev-parse --short HEAD`
Whenever local HEAD diverges from upstream — unpushed work, dirty stage
branches, forks, in-flight rebases, release-time merge commits whose SHA
only lives in the maintainer's local history — the compare URL points at
a SHA github.com has never seen and returns the standard 404 page.
Reporter (@ai-ag2026) observed:
c660c7f...86cb22e
→ 404 because c660c7f was an unpushed local commit.
The right base is `git merge-base HEAD <compare_ref>` — the most recent
commit local and upstream share. Since `git fetch` succeeded just before,
the merge-base is guaranteed to exist on the upstream GitHub repo.
Behavior matrix:
Pure-behind clone (no local commits): merge-base == HEAD; URL unchanged.
Behind + local-only commits (#1579): merge-base != HEAD; URL points at
public ancestor instead of local HEAD.
merge-base failure (shallow clone): current_sha=None; JS link guard
suppresses link rather than emitting
a known-broken URL.
Also hardens static/ui.js: reset the link's href and display:none on every
banner render, so a stale link from a prior render can't survive a re-render
where the new payload has current_sha=null.
Tests:
- test_current_sha_is_merge_base_not_local_HEAD — reporter's scenario
- test_current_sha_equals_HEAD_when_no_local_commits — backward compat
- test_current_sha_falls_back_to_None_when_merge_base_fails — defensive
- test_whats_new_link_resets_display_and_href_on_every_render
- test_whats_new_link_suppressed_when_curSha_falsy
- test_reporter_url_shape_no_longer_produces_invalid_compare_url
4094 → 4100 passing. 0 regressions.
3369a08f37
