We do not need to track object refs, neither we need to save commit
unless we are doing verbose header. A lot of traversal happens
inside prepare_revision_walk() these days so setting things up before
calling that function is necessary.
Signed-off-by: Junio C Hamano <junkio@cox.net> Acked-by: Linus Torvalds <torvalds@osdl.org>