revset: minor changes adding baseset to revsets

Changed bits of code to work with baseset implementations.

mercurial/revset.py

@@ -334,7 +334,7 b' def ancestorspec(repo, subset, x, n):'
         raise error.ParseError(_("~ expects a number"))
     ps = set()
     cl = repo.changelog
-    for r in getset(repo, cl, x):
+    for r in getset(repo, baseset(cl), x):
         for i in range(n):
             r = cl.parentrevs(r)[0]
         ps.add(r)