lazyset: directly use __contains__ instead of a lambda

We apply the same speedup as in spanset, getting rid of the useless lambda.
(No new timing, as this is the very same change)

mercurial/revset.py

@@ -2356,7 +2356,7 b' class lazyset(object):'
                 yield x
 
     def __and__(self, x):
-        return lazyset(self, lambda r: r in x)
+        return lazyset(self, x.__contains__)
 
     def __sub__(self, x):
         return lazyset(self, lambda r: r not in x)