evolve: always order the revs to be evolved
The current code only order the revs if we are resolving orphans and not in
other case. The ordering is important when we pass --all and tackle multiple
occurence of the same instability.
Let's order the revs for each instability. There are enough test coverage of
phase-divergence and content-divergence that I feel confident doing it because
none of the test changed.
The change in test-evolve-content-divergent.t demonstrates the indeed ordering
helped.