changegroup: fix fastpath during commit

Change 627cd7842e5d dropped the 'revset' variable which kept track of
which changesets were being bundled. Instead, it used "not in
commonset" to decide which changesets were outgoing.. which ran into
trouble when a commit was in progress.

mercurial/changegroup.py

@@ -364,10 +364,11 b' class bundle10(object):'
 
             if fastpathlinkrev:
                 ln, llr = filerevlog.node, filerevlog.linkrev
+                needed = set(cl.rev(x) for x in clnodes)
                 def genfilenodes():
                     for r in filerevlog:
                         linkrev = llr(r)
-                        if linkrev not in commonrevs:
+                        if linkrev in needed:
                             yield filerevlog.node(r), cl.node(linkrev)
                 fnodes[fname] = dict(genfilenodes())