Merge branch 'jk/ok-to-fail-gc-auto-in-rebase' into maint

"git rebase", unlike all other callers of "gc --auto", did not
ignore the exit code from "gc --auto".

* jk/ok-to-fail-gc-auto-in-rebase:
  rebase: ignore failures from "gc --auto"

git-rebase.sh

@@ -176,7 +176,7 @@ You can run "git stash pop" or "git stash drop" at any time.
 
 finish_rebase () {
 	apply_autostash &&
-	git gc --auto &&
+	{ git gc --auto || true; } &&
 	rm -rf "$state_dir"
 }