changegroup: remove one special case from lookupmflinknode

In the fastpathlinkrev case, lookupmflinknode was a very complicated
way of saying mfs.__getitem__, so let's just get that case out of our
way so it's easier to understand what's going on.

mercurial/changegroup.py

@@ -656,6 +656,9 b' class cg1packer(object):'
         # Callback for the manifest, used to collect linkrevs for filelog
         # revisions.
         # Returns the linkrev node (collected in lookupcl).
+        if fastpathlinkrev:
+            lookupmflinknode = mfs.__getitem__
+        else:
         def lookupmflinknode(x):
             """Callback for looking up the linknode for manifests.
 
@@ -664,13 +667,12 b' class cg1packer(object):'
             SIDE EFFECT:
 
               fclnodes gets populated with the list of relevant
-              file nodes if we're not using fastpathlinkrev.
+                  file nodes.
 
             Note that this means you can't trust fclnodes until
             after manifests have been sent to the client.
             """
             clnode = mfs[x]
-            if not fastpathlinkrev:
                 mdata = ml.readfast(x)
                 for f in mfchangedfiles[x]:
                     try: