Removing options from build

One of our developers "discovered" the --force option on `git push` and used it without taking the appropriate care and hosed one of the project branches we have running around in our central repository.

Besides a vigorous flogging, we're looking at other ways to prevent this sort of thing from happening again; the option we've settled on is to remove the "--force" flag from our internal build of v1.6.1

I'm wondering if somebody could point me in the right direction to remove "--force" (safely) from the builtin-push.c and removing the "rebase" command (we've got no use for it, and would prefer it gone).

Cheers