revlog: do not compute node location by hand in index_invalidate_added
The node is not guaranteed to be at the same location all the time (e.g:
changelog v2), so let's use the official existing API to get that value.
Differential Revision: https://phab.mercurial-scm.org/D12176
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}