evolve: dedupe divergents when running evolve --all --any or evolve --rev
Before this patch, when running evolve --all --any or evolve --rev with the
--divergent flag, we were selecting all of the divergents. After solving the
first one, its counterparts would get pruned and potentially hidden which would
crash when trying to resolve them. This patch introduces logic to dedupe the
divergents to be resolved by keeping only one per group of divergent with the
lower revision number.