diff -r 671aba341d90 -r 9700cb9df140 mercurial/scmutil.py
--- a/mercurial/scmutil.py	Wed Nov 22 20:49:01 2017 -0500
+++ b/mercurial/scmutil.py	Sun Nov 26 14:59:39 2017 -0500
@@ -1279,3 +1279,9 @@
             else:
                 revrange = '%s:%s' % (minrev, maxrev)
             repo.ui.status(_('new changesets %s\n') % revrange)
+
+def wrapconvertsink(sink):
+    """Allow extensions to wrap the sink returned by convcmd.convertsink()
+    before it is used, whether or not the convert extension was formally loaded.
+    """
+    return sink