stablerange: fix slicing of arbitrary ranges
Pull bundle trigger slicing from range with arbitrary initial skip. We have to
adjust the current slicing to take this into account.
# setup config and various utility to test new heads checks on push.$TESTDIR/testlib/common.shcat>>$HGRCPATH<<EOF[ui]# simpler log outputlogtemplate ="{node|short} ({phase}): {desc}\n"[phases]# non publishing serverpublish=False[extensions]# we need to strip some changeset for some test casesstrip=evolve=EOFsetuprepos(){echocreatingbasicserverandclientrepohginitservercdservermkcommitroothgphase--public.mkcommitA0cd..hgcloneserverclient}