tests: add tests for testing --abort while content-divergence resolution This patch adds a new test file with a very basic test of `--abort` on an interrupted evolve which was resolving content-divergence. Upcoming patches will add more rigourous tests.

evolve: fix storage of replacements and temprevs node in evolvestate The _completephaseivergent() was not respecting rules on how to store the new node ids created in evolvestate. The rules are: * store the temporary relocated commits in temprevs * store the final new commit in replacements This patch make sure we follow the above rules and also use the return value returned by _resolvephasedivergence(). The tests change demonstrates that we are all good now.

tests: add more tests related to aborting while resolving phase-divergence The tests shows the something is still broken related to abort while resolving phase-divergence which will be fixed in upcoming patches.

topic: suggest to clear a topic that becomes empty We add a hint suggesting "hg topic --clear" when a topic becomes empty. This usually happens when all its changesets get public, that is when the user does a 'phase -p' or when they pull from a server. To discriminate relevant cases for which we should display the hint (and typically exclude explicit 'hg topic --clear' operation), we look for the transaction "type" to only consider 'phase' or 'push' transaction. In the latter case, the transaction name is not simply 'push-response' but it also included the remote URL so we need to match on string content.

topic: display a hint pointing at help when a topic becomes non-empty This is an attempt at avoiding "mistakes" by new users of topics when they pull a topic and publish its changesets while being checked out. In this case, the topic will become empty but still be active; however, if this is a "foreign" topic, the user will not likely want to keep it active for the next commit operation. So we add a hint message pointing at general help of "topics" command so that they can eventually do something and learn about "hg topics --clear".

branching: merge with compat fix on default