false positives from git diff-index when used with --git-dir

Hi, list!

$ git --version git version 1.7.3.1

$ lsb_release -a No LSB modules are available. Distributor ID: Ubuntu Description: Ubuntu 10.10 Release: 10.10 Codename: maverick

I'm *sometimes* (once in about ten times I use it -- repository changes between invocations of course) getting false positives from git diff-index when I invoke git from another directory:

git --git-dir=path/to/.git --work-tree=path/to update-index -q --refresh git --git-dir=path/to/.git --work-tree=path/to diff-index --exit-code --quiet HEAD

This is *really* annoying and really kills the benifits from my workflow automation scripts.

Unfortunately I can't find a reproducible use case for this bug.

Is there anything I can do to help catch it?

Thanks, Alexander.