This should make it much easier to track newly added tags and
branches. Re-running multi-init without command-line arguments
should now detect new-tags and branches.
--trunk shouldn't change often, but running multi-init on it
is now idempotent.
Signed-off-by: Eric Wong <normalperson@yhbt.net> Signed-off-by: Junio C Hamano <junkio@cox.net>