repository: clarify role of imanifestlog Looking at the implementation of manifest.manifestlog, it is highly tailored towards servicing the root manifest. So clarify that in the interface docstring. Differential Revision: https://phab.mercurial-scm.org/D4273

changegroup: change topics during generation Changegroup generation and consumption currently uses different sets of topics. Generation uses "bundling" and consumption uses the name of the thing being consumed. This commit makes the topic and unit names consistent on both ends. The reason I chose to change the generation side is because when "bundling" is used for 3 different stages, it is unclear which stage of changegroup generation we're in. By making the topics "changesets," "manifests," and "files," one can get a better feel for how far along in the bundling process we are. Differential Revision: https://phab.mercurial-scm.org/D4272

changegroup: rename mfs to manifests In the name of readability. Differential Revision: https://phab.mercurial-scm.org/D4271

changegroup: clean up changelog callback changelog.read() calls changelog.changelogrevion() then turns it into a tuple. Let's call changelogrevision() directly and used named attributes to make code easier to read. While we're here, also change some variable names to make code easier to read. Differential Revision: https://phab.mercurial-scm.org/D4270