diff -r 408b7979bf03 -r 2afa748138e0 mercurial/sshpeer.py
--- a/mercurial/sshpeer.py	Wed May 20 10:58:29 2015 -0500
+++ b/mercurial/sshpeer.py	Fri Jun 05 04:54:23 2015 -0700
@@ -65,7 +65,7 @@
 
         (This will only wait for data if the setup is supported by `util.poll`)
         """
-        if self._main.hasbuffer:
+        if getattr(self._main, 'hasbuffer', False): # getattr for classic pipe
             return (True, True) # main has data, assume side is worth poking at.
         fds = [self._main.fileno(), self._side.fileno()]
         try: