[PATCH] Prevent git-rev-list without --merge-order producing duplicates in output

[PATCH] Prevent git-rev-list without --merge-order producing duplicates in output

If b is reachable from a, then:

	 git-rev-list a b

argument would print one of the commits twice.

This patch fixes that problem. A previous problem fixed it for the
--merge-order switch.

Signed-off-by: Jon Seymour <jon.seymour@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>