revlog: store new index entries as binary For a pure-Python unbundle of the current NetBSD test repository, this results in a 10% peak RSS reduction. Using the C revlog index, it shows 25% peak RSS reduction. This is a direct result of avoiding at least 8 objects per new changeset or 200 Bytes+ on AMD64. Differential Revision: https://phab.mercurial-scm.org/D9162