shelve: really pass publicancestors to changegroupsubset - not the parents

publicancestors returned the parents of the public ancestors ... and
changegroupsubset used the parents of these as base for the bundle. That gave
bundles with one layer of changesets more than necessary.

hgext/shelve.py

@@ -122,22 +122,21 b' def createcmd(ui, repo, pats, opts):'
     """subcommand that creates a new shelve"""
 
     def publicancestors(ctx):
-        """Compute the heads of the public ancestors of a commit.
+        """Compute the public ancestors of a commit.
 
-        Much faster than the revset heads(ancestors(ctx) - draft())"""
+        Much faster than the revset ancestors(ctx) & draft()"""
         seen = set([nullrev])
         visit = util.deque()
         visit.append(ctx)
         while visit:
             ctx = visit.popleft()
+            yield ctx.node()
             for parent in ctx.parents():
                 rev = parent.rev()
                 if rev not in seen:
                     seen.add(rev)
                     if parent.mutable():
                         visit.append(parent)
-                    else:
-                        yield parent.node()
 
     wctx = repo[None]
     parents = wctx.parents()