upgrade: prepare code (and output) for the idea of upgrading share
This would work for a subset of action only. Our first target is dirstate-v2.
Differential Revision: https://phab.mercurial-scm.org/D12196
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}