revset: extract a helper to parse integer range
It's getting common. As a first step, this patch adds getintrange() and
makes followlines() use it.
I wanted to unify the error messages to make the function interface simple,
but I failed to phrase it briefly.
{
"conduit_uri": "https://phab.mercurial-scm.org/api",
"repository.callsign": "HG",
"arc.land.onto.default": "@",
"base": "hg:.^"
}