diff -r 50d2389a2e49 -r 91786f20db83 mercurial/subrepo.py
--- a/mercurial/subrepo.py	Tue Nov 10 14:26:19 2015 -0800
+++ b/mercurial/subrepo.py	Tue Nov 10 14:29:13 2015 -0800
@@ -1910,7 +1910,7 @@
             status = self.status(None)
             names = status.modified
             for name in names:
-                bakname = "%s.orig" % name
+                bakname = cmdutil.origpath(self.ui, self._subparent, name)
                 self.ui.note(_('saving current version of %s as %s\n') %
                         (name, bakname))
                 self.wvfs.rename(name, bakname)