split: remove an unnecessary (and confusingly typed) fallback revision `opts.get('rev') or '.'` is either a list of strings or just a string. It happened to work because `'.'[0] == '.'` on Python 2, but it won't work on Python 3 (for byte strings). The fallback value wasn't even needed (it was also set just after), so let's just remove it.

evolve: rename variable "children" to "child" where it's clearly singular

evolve: remove some unused variables

py3: back out 23323092f0a7 D6623 has now been accepted in Mercurial (commit 83666f011679), so evolve commit 23323092f0a7 (py3: convert _origdoc to sysstr to match __doc__, 2019-07-09) is not longer needed.

branching: merge with stable

touch: fix the inconsistent behavior of divergence catching logic (issue6107) When touching a node, the way we check if it can lead to divergence is we look at the successors sets of the rev being touched. And if there is successor revs exists (excluding the case when that successor set is (A,) for rev A) that means there will be divergence and we warn the user. This works fine but there is still a case (which is not covered by looking at successor sets) which can lead to divergence. That case is: when there is already a revision exists which is divergent to the revision being touched. And performing the touch would revive that "dead" divergence. (Dead because one of the revision is obsolete which is the one we are touching) And to see if there is any rev which is divergent to a particular rev we already have a function which we can use here i.e. `evolvecmd.divergentsets(repo, ctx_being_touched)` Changes in test file demonstrate the fixed behaviour.

touch: add test which shows touch can fail to warn about divergence