diff -r 99362821b25b -r 1e3e064c16a1 mercurial/subrepo.py
--- a/mercurial/subrepo.py	Tue Mar 03 21:24:16 2015 -0500
+++ b/mercurial/subrepo.py	Tue Mar 03 21:31:16 2015 -0500
@@ -1662,7 +1662,7 @@
 
         deleted, unknown, ignored, clean = [], [], [], []
 
-        if not rev2:
+        if opts.get('unknown'):
             command = ['ls-files', '--others', '--exclude-standard']
             out = self._gitcommand(command)
             for line in out.split('\n'):