pick: actually delete pickstate if --abort is given Makes pick to be, uh, actually aborted.

evolve: orphans that evolve into nothing don't need successors (issue5967) When continuing to solve an orphan that created no changes (i.e. clean wdir), _completeorphan() used to create an obsmarker that said that the result of that orphan evolution is the currently checked out changeset. That's not a correct obsmarker, because all of the orphan's changes were dropped and so it had no effect on the currently checked out changeset. This is an issue that has only existed when --continu'ing evolve, that's why the fix touches _completeorphan(), but not _solveunstable(). This fix is adapted from a similar "if node is None" block in _finalizerelocate().

tests: demonstrate obsmarker creation after discarding conflicting changes Continued evolve creates an incorrect obsmarker that says 2 is a successor of 1. It's incorrect because 1 was dropped as it created no changes to commit (after conflict resolution that discarded its changes). If evolve does the same thing in one go (e.g. just by using --tool :local and without subsequent need to continue) the obsmarker is correct.