diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -428,3 +428,20 @@ class bundle10(object):
     def builddeltaheader(self, node, p1n, p2n, basenode, linknode):
         # do nothing with basenode, it is implicitly the previous one in HG10
         return struct.pack(self.deltaheader, node, p1n, p2n, linknode)
+
+def getsubset(repo, outgoing, bundler, source, fastpath=False):
+    repo = repo.unfiltered()
+    commonrevs = outgoing.common
+    csets = outgoing.missing
+    heads = outgoing.missingheads
+    # We go through the fast path if we get told to, or if all (unfiltered
+    # heads have been requested (since we then know there all linkrevs will
+    # be pulled by the client).
+    heads.sort()
+    fastpathlinkrev = fastpath or (
+            repo.filtername is None and heads == sorted(repo.heads()))
+
+    repo.hook('preoutgoing', throw=True, source=source)
+    repo.changegroupinfo(csets, source)
+    gengroup = bundler.generate(commonrevs, csets, fastpathlinkrev, source)
+    return unbundle10(util.chunkbuffer(gengroup), 'UN')
diff --git a/mercurial/exchange.py b/mercurial/exchange.py
--- a/mercurial/exchange.py
+++ b/mercurial/exchange.py
@@ -181,10 +181,11 @@ def _pushchangeset(pushop):
         # push everything,
         # use the fast path, no race possible on push
         bundler = changegroup.bundle10(pushop.repo, bundlecaps)
-        cg = pushop.repo._changegroupsubset(outgoing,
-                                            bundler,
-                                            'push',
-                                            fastpath=True)
+        cg = changegroup.getsubset(pushop.repo,
+                                   outgoing,
+                                   bundler,
+                                   'push',
+                                   fastpath=True)
     else:
         cg = pushop.repo.getlocalbundle('push', outgoing, bundlecaps)
 
diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -1714,7 +1714,7 @@ class localrepository(object):
             discbases.extend([p for p in cl.parents(n) if p != nullid])
         outgoing = discovery.outgoing(cl, discbases, heads)
         bundler = changegroup.bundle10(self)
-        return self._changegroupsubset(outgoing, bundler, source)
+        return changegroup.getsubset(self, outgoing, bundler, source)
 
     def getlocalbundle(self, source, outgoing, bundlecaps=None):
         """Like getbundle, but taking a discovery.outgoing as an argument.
@@ -1724,7 +1724,7 @@ class localrepository(object):
         if not outgoing.missing:
             return None
         bundler = changegroup.bundle10(self, bundlecaps)
-        return self._changegroupsubset(outgoing, bundler, source)
+        return changegroup.getsubset(self, outgoing, bundler, source)
 
     def getbundle(self, source, heads=None, common=None, bundlecaps=None):
         """Like changegroupsubset, but returns the set difference between the
@@ -1747,24 +1747,6 @@ class localrepository(object):
                                    discovery.outgoing(cl, common, heads),
                                    bundlecaps=bundlecaps)
 
-    @unfilteredmethod
-    def _changegroupsubset(self, outgoing, bundler, source,
-                           fastpath=False):
-        commonrevs = outgoing.common
-        csets = outgoing.missing
-        heads = outgoing.missingheads
-        # We go through the fast path if we get told to, or if all (unfiltered
-        # heads have been requested (since we then know there all linkrevs will
-        # be pulled by the client).
-        heads.sort()
-        fastpathlinkrev = fastpath or (
-                self.filtername is None and heads == sorted(self.heads()))
-
-        self.hook('preoutgoing', throw=True, source=source)
-        self.changegroupinfo(csets, source)
-        gengroup = bundler.generate(commonrevs, csets, fastpathlinkrev, source)
-        return changegroup.unbundle10(util.chunkbuffer(gengroup), 'UN')
-
     def changegroup(self, basenodes, source):
         # to avoid a race we use changegroupsubset() (issue1320)
         return self.changegroupsubset(basenodes, self.heads(), source)