compat: drop 4.3 monkey patch of `copies.mergecopies`

compat: drop 4.3 compatiblity code for `obsutil.allprecursors` function

compat: drop 4.3 compatiblity code for `ui.edit` method

compat: drop 4.3 compatiblity code for 'successors' revset

compat: drop 4.3 compatiblity code for 'precursors' revset

compat: drop Mercurial 4.3 support for exthelper The last release email noted plans to drop 4.3 and 4.4 support in the next feature release. I'd like to move this code into core, and dropping this should allow the class to be copied in unmodified.

compat: update metadata about minimum ag version

next: solve the issue of `next` get confused by split This patch solve a problem of next command which get confused by split. Let me describe how it was getting confused: Initial state of repo: A---B---C After splitting B to (B1,B2): @ A---B1---B2 \ ---B---C X * (note: C is orphan; checkedout to B1) Lets make an amend on B1: @ B1' / A---B1---B2 \ X * \ ---B---C X * Now, if run `hg next` (--evolve is True by default now): $ it would give you choice to choose from B2 and C thinking that C could also be a possbile children for B1, instead of stablizing B2 on B1. I fixed this problem by filtering those aspiring children which can be stablized on one of the aspiring children itself. Changes made in test-prev-next.t shows the changed expected behaviour.

next: add test which shows that `next` get confused by split

cleanup: avoid a Yoda condition