evolve: fix an issue in the documentation of the evolve function hg evolve is solving troubles that will become children of the parent of the working copy and its descendant. This last part was omitted by mistake from the help message before.

evolve: fix error in builddependencies When MultipleSuccessorsError was raised, we were still running the code below to add the dependency if succ was not None from a previous iteration. This bug was harmless because dependencies and rdependencies are sets but it makes the code clearer this way.