utility: add a function to prompt user to choose a revision This patch adds a utility function to interactively prompt user to choose a revision to proceed in cases when there are multiple revisions which are candidates. The function will be used in `hg evolve`, `hg next`, `hg prev` etc. If user feedback will be good, I plan to move it to core and use it at more possible places.

tests: add a test about evolve stabilizing orphan caused by splits There are some similar tests lying around in the test suite but they are not well arranged. I wanted the test suite to be a goto reference for all the behaviors till the time we get all of them documented.

test: fix output after rev-branch-cache has been merged Mercurial core 2090044a288d added a new revbranchcache part which changed some exchange-related outputs. Glob them to ease merging with old Mercurial versions branches.