evolve: add evolvestate as an argument to evolvecmd.relocate()
This will help us in passing it to _finalizerelocate() and store the bookmark
changes which happend.
tests: add test about handling phase-divergent merges
We don't handle phase-divergent merges and we should. Upcoming patches will add
the ability to handle them.
evolve: show a message when evolution leads to no changes to commit
In case of orphan resolution, evolution may result in no changes to commit. This
patch adds a use message in such cases. This is same as the rebase behavior.