On 9 Dec 2012, Timothy Pearson verbalised:
What I would really like to see in GIT is the ability to track submodule HEAD refs in a supermodule without needing to establish a ridiculously long commit history containing every submodule change.
I hate to ask this but... what harm is there in that? git doesn't get harmed at all by very long histories. All you're storing is a few extra hashes.