merge with future 5.5 No extra change needed to get the test to passe with 3.6

merge with future 5.5 No extra new change are needed from the one needed from the 3.8 branch and previous version.

merge with future 5.5 Test also run on 3.8 with minor cosmetic change. The 'separate' function is not available before 3.9 so we had to drop it.

integrate code update and test change from future 5.5 code This prove that the code is compatible with 3.9

merge with default, Mercurial 4.0-rc is out The content of the Mercurial stable branch changed, we update it here too.

open the mercurial-3.9 compat branch

merge with stable

evolve: lock the working copy early in next and prev (issue5244) Both next and prev depend on a consistent working copy, but were waiting to take the lock until they were ready to alter the working copy. Take the lock before reading the working copy state, and do not release it until we're definitely not going to change the working copy.

evolve: indent cmdnext and cmdprev ready for locking change (issue5244) The locking change I'm about to introduce forces an indentation shift. Do the indentation change with no code change now, to make the next change easier to review

tests: adapt to some change to topic output

split: avoid trying to split an empty commit (issue5191)

split: avoid trying to split an empty commit (issue5191)