shelve: adjust what happens in some `changing_parents` context
It seems like the rest is more about changing tracked_files, so we let start
with moving them out of the `changing_parents` contexts.
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}