suggested feature: completely expunge a file (or just a delta) a la rebase

Here's an idea for a git feature. (Or perhaps this is already possible and I just don't see it.)

It would be nice to be able to completely expunge a file or delta from a private part of an archive ("private" meaning not yet published to others).

Here's my use case. I have some unit tests for my program, and I added some input and output for the tests to my git archive. Now I'm having second thoughts, as these files can be quite large, and I'm realizing what this implies with respect to git. Even the smallish test cases I checked in are 5-10MB, which is way larger than the codebase, and I'm not sure it makes sense to drag all of this around in the git archive. (Maybe it would be appropriate to put them in a parallel archive?)

Anyway, I realized that hacking the archive this way isn't very elegant, but maybe others would find it useful. It seems like the basic technique of git-rebase could be applied here.

Even if the archive is already public, I suppose it might occasionally be useful to be able to (say) split the archive by subtrees, and simply have everyone cut over.

Mike