diff --git a/hgext/narrow/narrowchangegroup.py b/hgext/narrow/narrowchangegroup.py
--- a/hgext/narrow/narrowchangegroup.py
+++ b/hgext/narrow/narrowchangegroup.py
@@ -12,7 +12,6 @@ from mercurial import (
     changegroup,
     error,
     extensions,
-    manifest,
     mdiff,
     node,
     pycompat,
@@ -21,15 +20,6 @@ from mercurial import (
 )
 
 def setup():
-    def prune(orig, self, revlog, missing, commonrevs):
-        if isinstance(revlog, manifest.manifestrevlog):
-            if not self._filematcher.visitdir(revlog._dir[:-1] or '.'):
-                return []
-
-        return orig(self, revlog, missing, commonrevs)
-
-    extensions.wrapfunction(changegroup.cg1packer, 'prune', prune)
-
     def generatefiles(orig, self, changedfiles, linknodes, commonrevs,
                       source):
         changedfiles = list(filter(self._filematcher, changedfiles))
diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -21,6 +21,7 @@ from .node import (
 from . import (
     dagutil,
     error,
+    manifest,
     match as matchmod,
     mdiff,
     phases,
@@ -589,6 +590,11 @@ class cg1packer(object):
 
     # filter any nodes that claim to be part of the known set
     def prune(self, revlog, missing, commonrevs):
+        # TODO this violates storage abstraction for manifests.
+        if isinstance(revlog, manifest.manifestrevlog):
+            if not self._filematcher.visitdir(revlog._dir[:-1] or '.'):
+                return []
+
         rr, rl = revlog.rev, revlog.linkrev
         return [n for n in missing if rl(rr(n)) not in commonrevs]