git branch --delete-merged <branch>...
deletes the local branches that "--forked <branch>" would list,
keeping only those whose tip is reachable from their configured
upstream. The work has already landed on the upstream they track,
so the local copy is no longer needed.
A branch is not deleted when:
* it is checked out in any worktree
* its upstream remote-tracking branch no longer exists, since a
missing upstream is not by itself a sign of integration
* its push destination equals its upstream (<branch>@{push} is
the same as <branch>@{upstream}), such as a local "main" that
tracks and pushes to "origin/main". Right after a pull it just
looks "fully merged", so it is kept. Only branches that push
somewhere other than their upstream, typically topics in a fork
workflow, are candidates.
A branch whose work is not yet merged into its upstream is silently
skipped, so one unmerged topic does not abort the whole sweep.
A branch that another, surviving branch tracks as its upstream is
also kept, so a branch is never deleted out from under one stacked
on top of it. Such a kept branch is itself merged, so when its own
upstream is being deleted, clear its now-stale upstream config.
Signed-off-by: Harald Nordgren <haraldnordgren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
7b6e901ec8