.arcconfig

fileset: restrict getfileset() to not return a computed set (API)

And rename the functions accordingly. fileset.match() will be changed to
not compute the initial subset.

test-glog*.t get back to the state before 9f9ffe5f687c "match: compose
'set:' pattern as matcher."

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}