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.