Libify puzzle

Hi,

I was just thinking a bit about teaching git-blame about renames, and hit 
a problem: When rev-list stops because none of the parents has the file of 
interest, the program should look if the parents contained a similar file 
which got deleted. But the commit's parents were explicitely culled!

The problem seems to affect more programs when we try to libify them: What 
used to be a pipe between two programs, can no longer just set 
save_commit_buffer = 0 in the first stage, since the second might depend 
on the buffer.

Would the correct solution be something like reparse_commit(commit)?

Ciao,
Dscho