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