Allow building of RPM from interim snapshot.

Allow building of RPM from interim snapshot.

By popular demand.  If you build and install such binary RPMs,
the version numbering will lose monotonicity, so you may have to
later override downgrade warnings from your packaging manager,
but as long as you are aware of that and know how to deal with it,
there is no reason for us to forbid it.

Signed-off-by: Junio C Hamano <junkio@cox.net>