changegroup: stop returning and recording added nodes in 'cg.apply'

cg.apply used to returns the added nodes. Callers doesn't have a use for it
anymore, remove the added node and stops recording it in the current
operation.

This information was added in the current release cycle so no extensions
breakage should happens.

mercurial/bundle2.py

@@ -403,10 +403,9 b' def processbundle(repo, unbundler, trans'
     return op
 
 def _processchangegroup(op, cg, tr, source, url, **kwargs):
-    ret, addednodes = cg.apply(op.repo, tr, source, url, **kwargs)
+    ret = cg.apply(op.repo, tr, source, url, **kwargs)
     op.records.add('changegroup', {
         'return': ret,
-        'addednodes': addednodes,
     })
     return ret
 

mercurial/changegroup.py

@@ -412,7 +412,7 b' class cg1unpacker(object):'
             ret = deltaheads - 1
         else:
             ret = deltaheads + 1
-        return ret, added
+        return ret
 
 class cg2unpacker(cg1unpacker):
     """Unpacker for cg2 streams.