next-prev: replace the error hint to mention about `--merge` flag

tests: add tests for conflicts while respecting commands.update.check This patch adds tests to check that we don't run into conflicts while respecting commands.update.check. The error message now does not show the hint about --merge option which we should fix.

next: respect `commands.update.check` config option in `hg next` (issue5808) `commands.update.check` config option determines what level of checking should be done when we update to another revision. When we set this config option to `noconflict`, it updates your working directory to a specified revision only when there will be no conflicts which is a very nice behavior. This patch adds logic to respect the config option so that we can have that nice behavior with `hg next` too. It turns out, we just needed to use hg.updatetotally() and add some cases to check config option. Right now, we only respect the config if value is set to `noconflict`. Otherwise we fallback to the default behavior. This is a part of fixing issue5808. Test changes demonstrate the fix.

prev: respect `commands.update.check` config option in `hg prev` (issue5808) `commands.update.check` config option determines what level of checking should be done when we update to another revision. When we set this config option to `noconflict`, it updates your working directory to a specified revision only when there will be no conflicts which is a very nice behavior. This patch adds logic to respect the config option so that we can have that nice behavior with `hg prev` too. It turns out, we just needed to use hg.updatetotally() and add some cases to check config option. Right now, we only respect the config if value is set to `noconflict`. Otherwise we fallback to the default behavior. This is a part of fixing issue5808. Test changes demonstrate the fix.

tests: add test demonstrating issue5808 This patch adds test showing that `next` and `prev` does not respect the `commands.update.check` config option, particularly when set to `noconflict`.

next: bail out early in `hg next --evolve` if dirty wdir This patch adds logic to bail out early when --evolve is passed with next command and the working directory is dirty. This will help us in preventing the message saying `do you want --merge` which is useless and misleading when `--evolve` is passed.

tests: add test of `hg next --evolve` with dirty working directory I was testing some output change to `hg next --evolve` in dirty working directory and found that we don't have any test for that.

CHANGELOG: add an entry about fixing issue5897

evolve: fix `hg abort` when hg next --evolve leads to conflicts (issue5897) Before this patch, if you do `hg next --evolve` and end up having conflicts and then you try `hg abort`, it will throw a KeyError. This patch fixes that.

tests: add a test demonstrating issue5897 When conflicts are caused due to `hg next --evolve`, `hg evolve --abort` breaks! This patch adds test to demonstrate that. This will be fixed in next patch.

evolve: add an `--update` flag to `hg evolve` command This patch adds a new `--update` flag which defaults to True. The update flag updates the working directory to the head of evolved revisions after `hg evolve` command. This flag can be used to not update your working directory after `hg evolve` which has been one of the biggest feature request from fig team at Google. To not update your working directory, the user can do `hg evolve --no-update`. If the working directory get obsoleted by evolve command, it will update to the successor. This patch also adds some basic tests for the flag introduced.

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".