--- a/mercurial/cmdutil.py	Wed Jun 08 14:54:52 2011 +0300
+++ b/mercurial/cmdutil.py	Wed Jun 08 14:54:52 2011 +0300
@@ -160,7 +160,7 @@
     writable = mode not in ('r', 'rb')
 
     if not pat or pat == '-':
-        fp = writable and sys.stdout or sys.stdin
+        fp = writable and repo.ui.fout or repo.ui.fin
         return os.fdopen(os.dup(fp.fileno()), mode)
     if hasattr(pat, 'write') and writable:
         return pat