rebase: refactoring to avoid repetition of expression This patch removes the repetition of "(revignored, revprecursor, revpruned)" and replaces its occurences with the more legible "revskipped".

rebase: remove an unused todo Since we handled skipping obsolete revs when it is relevant, this todo is no longer useful. We replace the comment with two useful comments.

rebase: don't rebase obsolete commits with no successor This patch avoids unnecessary conflicts to resolve during rebase for the users of changeset evolution. This patch modifies rebase to skip obsolete commits with no successor. It introduces a new rebase state 'revpruned' for these revisions that are being skipped and a new message to inform the user of what is happening. This feature is gated behind the config flag experimental.rebaseskipobsolete When an obsolete commit is skipped, the output is: note: not rebasing 7:360bbaa7d3ce "O", it has no successor