delta-find: move pre-filtering of individual revision in its own function
This goes one step further than the previous change by making the pre-filtering
of individual candicates revision in its own function. This will allow subclass
to easily configure this filtering with their own constrains.
The `if True:` part help the readability of this diff a lot and will be drop in
to the next changesets.
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"phabricator.uri": "https://phab.mercurial-scm.org/",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}