builddependencies: consider all divergent successors We were only considering one. In test-evolve-abort-conentdiv.t:165, the input revs were {5, 8} and dependency dict was {8: set([]), 5: set([10])}, which is a little weird (10 is not in the input set). It still worked because the callers used it (they seemed to only care if there were *any* dependencies). This patch fixes the issue by considering all successors. That means the dependency dict will be {8: set([]), 5: set([8, 10])} after this patch. The next patch will remove the 10 from that set.