rust: clean remains of direct-ffi code

Since b55bec1ea972, the cext entry poitn have been removed, so we drop the code
for consistency.

mercurial/ancestor.py

@@ -393,39 +393,3 b' class lazyancestors(object):'
             # free up memory.
             self._containsiter = None
             return False
-
-
-class rustlazyancestors(object):
-    def __init__(self, index, revs, stoprev=0, inclusive=False):
-        self._index = index
-        self._stoprev = stoprev
-        self._inclusive = inclusive
-        # no need to prefilter out init revs that are smaller than stoprev,
-        # it's done by rustlazyancestors constructor.
-        # we need to convert to a list, because our ruslazyancestors
-        # constructor (from C code) doesn't understand anything else yet
-        self._initrevs = initrevs = list(revs)
-
-        self._containsiter = parsers.rustlazyancestors(
-            index, initrevs, stoprev, inclusive
-        )
-
-    def __nonzero__(self):
-        """False if the set is empty, True otherwise.
-
-        It's better to duplicate this essentially trivial method than
-        to subclass lazyancestors
-        """
-        try:
-            next(iter(self))
-            return True
-        except StopIteration:
-            return False
-
-    def __iter__(self):
-        return parsers.rustlazyancestors(
-            self._index, self._initrevs, self._stoprev, self._inclusive
-        )
-
-    def __contains__(self, target):
-        return target in self._containsiter

mercurial/revlog.py

@@ -945,9 +945,6 b' class revlog(object):'
         if rustancestor is not None:
             lazyancestors = rustancestor.LazyAncestors
             arg = self.index
-        elif util.safehasattr(parsers, b'rustlazyancestors'):
-            lazyancestors = ancestor.rustlazyancestors
-            arg = self.index
         else:
             lazyancestors = ancestor.lazyancestors
             arg = self._uncheckedparentrevs