evolve: backout 3027005c42c3 to reintroduce a bug for right fix This patch backout 3027005c42c3 as it was accepted by mistake while it was being "in-discussion" state.

pick: register pickstate as an unfinished state This way pickstate file will indicate that unfinished pick command needs to be dealt with (--continue or --abort) before modifying the repo. Otherwise it would be e.g. possible to commit during an interrupted pick and that's not expected.