changegroup: pass ellipsis roots into cgpacker constructor And rename the internal variable to conform with naming conventions. Differential Revision: https://phab.mercurial-scm.org/D4089

changegroup: move revision maps to cgpacker And remove the underscores so the variables conform to our naming convention. The logic in _close() should be the only thing warranting scrutiny during review. Differential Revision: https://phab.mercurial-scm.org/D4088

changegroup: move changelogdone into cgpacker Looking at what it is used for, it feels like there is a better way to implement all this. So recording a TODO to track that. Differential Revision: https://phab.mercurial-scm.org/D4087

changegroup: declare shallow flag in constructor Thus begins the process of better formalizing ellipses and shallow changegroup generation mode so it is tracked by cgpacker at construction time instead of bolted on after the fact by a wrapper function. Differential Revision: https://phab.mercurial-scm.org/D4086

changegroup: make some packer attributes private These methods and attributes are low level and should not be called or outside outside of instances. Indicate as such through naming. Differential Revision: https://phab.mercurial-scm.org/D4085

changegroup: rename cg1packer to cgpacker There is now only a single class. We don't need to encode the version in its name since the version is a lie. Differential Revision: https://phab.mercurial-scm.org/D4084

changegroup: control delta parent behavior via constructor The last remaining override on cg2packer related to parent delta computation. We pass a parameter to the constructor to control whether to delta against the previous revision and we inline all parent delta logic into a single function. With this change, cg2packer is empty, so it has been deleted. Differential Revision: https://phab.mercurial-scm.org/D4083