Martin von Zweigbergk <martinvonz@google.com> [Fri, 20 Jul 2018 22:26:28 -0700] rev 38885
index: store nullrev as -1 in nodetree
Nothing important, it just seems more natural to not map nullrev to
INT_MAX. We just need to change the revision encoding a little to make
space for the -1.
Differential Revision: https://phab.mercurial-scm.org/D4005