git: restore basic functionality after b3040b6739ce We don't yet have a formal interface for the changelog, but it's mostly specified. Sadly, b3040b6739ce added a semi-private pseudo-enum that we need to cope with, so it's probably high time that someone (me?) attempts to define that interface to prevent future backsliding. Differential Revision: https://phab.mercurial-scm.org/D8992