git filter-branch should run git gc --auto

I just glanced at git-filter-branch.sh (and I must say I was incredibly surprised to find out it was a shell script) and it seems it never runs git-gc or git-repack. Doesn't that end up with the same problems as git-svn sans git-repack when filtering a large number of commits? I was just thinking, if I were to git-filter-branch on my massive repo (in fact, the same repo that started this thread, with over 33000 commits in the upstream svn repo), even if I just do something as simple as change the commit msg wont I end up with thousands of unreachable objects? I shudder to think how many unreachable objects I would have if I pruned the entire dports directory off of the tree.

Am I missing something, or does git-filter-branch really not do any garbage collection? I tried reading the source, but complex bash scripts are almost as bad as perl in terms of readability.

-Kevin Ballard