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git-sync: also mirror every branch the fork shares with upstream

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The fork's copies of long-lived branches (demo-20, totara-19, lms) drifted
over a thousand commits behind upstream because only the default branch was
ever synced. Fast-forward each branch present on both remotes straight from
upstream's ref and push them in one go; skip and warn on divergence, and leave
a local copy alone if it carries commits of its own.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
This commit is contained in:
Jonny Barnes 2026-09-10 09:16:21 +01:00
commit 24cb4c110a
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1 changed files with 36 additions and 4 deletions
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40
bin/git-sync
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@ -2,8 +2,9 @@
# Bring the default branch up to date in a fork-model repo, and keep my fork's
# copy of it aligned: fast-forward it from whichever remote owns it, then push
# it to origin. Named git-sync and installed on the $PATH, so git finds it as
# `git sync`.
# it to origin. Then do the same, without checking anything out, for every
# other branch the fork mirrors from upstream. Named git-sync and installed on
# the $PATH, so git finds it as `git sync`.
set -e
@ -62,6 +63,37 @@ fi
# something to look at, not something to paper over.
git merge --ff-only $source_remote/$branch
if [[ $source_remote != origin ]]; then
git push origin $branch
if [[ $source_remote == origin ]]; then
exit 0
fi
git push origin $branch
# Every branch that exists on both remotes is one the fork mirrors (release
# branches, demo branches), so keep those current too. Branches only on
# upstream are colleagues' work, not mine to copy. Nothing is checked out here:
# origin is updated straight from upstream's ref, and a local copy is
# fast-forwarded in place if there is one.
git fetch --prune origin
refspecs=()
for other in $(git for-each-ref --format='%(refname:strip=3)' refs/remotes/$source_remote/); do
[[ $other == $branch || $other == HEAD ]] && continue
git show-ref --verify --quiet refs/remotes/origin/$other || continue
if git merge-base --is-ancestor origin/$other $source_remote/$other; then
# Fast-forward a local copy too, but leave one with local commits
# alone: that is my in-progress work, not drift.
if git show-ref --verify --quiet refs/heads/$other &&
git merge-base --is-ancestor $other $source_remote/$other; then
git fetch . $source_remote/${other}:refs/heads/$other
fi
refspecs+=("$source_remote/${other}:refs/heads/$other")
else
echo "git sync: skipping $other - origin has diverged from $source_remote" >&2
fi
done
if (( ${#refspecs} )); then
git push origin "${refspecs[@]}"
fi