stablesort: use 'depth' in mergepoint tie breaker The parents with the most depth will is considered lower. It has a couple of advantages. 1) the more shallow parent probably have less exclusive revision, 2) it makes Oedipus merge behave like close to the linear case,

test-drop.t
test-inhibit.t
test-simple4server.t
tests/test-simple4server-bundle2.t