bug report: mutual recursion in the git-subtree shell script

[ resending bug report from git-users since there weren't any responses ]

So I'm trying to split out a directory from postgres source code
(which has 52k commits). I was able to split a directory into a
separate subtree (with 1685 commits). All good so far.

Now I do a pull from upstream and want to push the directory to my
subtree. The command fails with:

$ git subtree push --prefix=src/interfaces/libpq libpq master
/usr/lib/git-core/git-subtree: 647: Maximum function recursion depth
(1000) reached

As far as I can see, it seems to be a mutual recursion between

process_split_commit() and check_parents()

If this diagnosis is correct, are there any known workarounds? I've
tried increasing ulimit -s and FUNCNEST=10000, but it didn't fix the
problem.

Can this flow be coded without using recursion? Are there
implementations of git-subtree in another language which doesn't have
this problem?

 -Arun