rebase: fix path auditing to audit path relative to repo root (issue5818) Before this patch, when rebasing a file called "foo/bar", we would check e.g. if "/foo" (i.e. rooted at the file system root) was a symlink. Differential Revision: https://phab.mercurial-scm.org/D5361

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