branchmap: stop useless rev -> node -> rev round trip

We never use the node of new revisions unless in the very specific case of
closed heads. So we can just use the revision number.

So give another handfull of percent speedup.

mercurial/branchmap.py

@@ -230,17 +230,15 b' class branchcache(dict):'
         getbranchinfo = cl.branchinfo
         for r in revgen:
             branch, closesbranch = getbranchinfo(r)
-            node = cl.node(r)
-            newbranches.setdefault(branch, []).append(node)
+            newbranches.setdefault(branch, []).append(r)
             if closesbranch:
-                self._closednodes.add(node)
+                self._closednodes.add(cl.node(r))
         # if older branchheads are reachable from new ones, they aren't
         # really branchheads. Note checking parents is insufficient:
         # 1 (branch a) -> 2 (branch b) -> 3 (branch a)
-        for branch, newnodes in newbranches.iteritems():
+        for branch, newheadrevs in newbranches.iteritems():
             bheads = self.setdefault(branch, [])
             bheadrevs = [cl.rev(node) for node in bheads]
-            newheadrevs = [cl.rev(node) for node in newnodes]
             ctxisnew = bheadrevs and min(newheadrevs) > max(bheadrevs)
             # Remove duplicates - nodes that are in newheadrevs and are already
             # in bheadrevs.  This can happen if you strip a node whose parent