revbranchcache: factor logic to write names and revs in separate functions
Before this patch, the write function was so populated with upto 4 level of
indentation, it was hard to understand what's going on.
Differential Revision: https://phab.mercurial-scm.org/D6291
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}