changegroup: inline _packmanifests() into generatemanifests() It is relatively small. Every other generate*() calls group() directly. So the new code is consistent. Differential Revision: https://phab.mercurial-scm.org/D4198

changegroup: invert conditional and dedent I don't like seeing code that visually resembles the pyramid of doom. Differential Revision: https://phab.mercurial-scm.org/D4197

changegroup: make _revisiondeltanarrow() a standalone function It doesn't require any state on the packer. Everything impacting behavior is passed in as a function. So split it out, just like what was done for _revisiondeltanormal(). Differential Revision: https://phab.mercurial-scm.org/D4196