changegroup: replace changegroupsubset with makechangegroup
As part of getting rid of all the permutations of changegroup creation, let's
remove changegroupsubset and call makechangegroup instead. This moves the
responsibility of creating the outgoing set to the caller, but that seems like a
relatively reasonable unit of functionality for the caller to have to care about
(i.e. what commits should be bundled).
Differential Revision: https://phab.mercurial-scm.org/D665
Our full contribution guidelines are in our wiki, please see:
https://www.mercurial-scm.org/wiki/ContributingChanges
If you just want a checklist to follow, you can go straight to
https://www.mercurial-scm.org/wiki/ContributingChanges#Submission_checklist
If you can't run the entire testsuite for some reason (it can be
difficult on Windows), please at least run `contrib/check-code.py` on
any files you've modified and run `python contrib/check-commit` on any
commits you've made (for example, `python contrib/check-commit
273ce12ad8f1` will report some style violations on a very old commit).