[PATCH] ui: use self._isatty() for consistency

[Yuya Nishihara]

# HG changeset patch
# User Yuya Nishihara <yuya at tcha.org>
# Date 1412767116 -32400
#      Wed Oct 08 20:18:36 2014 +0900
# Node ID e4b2beb54fbd39980b3dd7c5a263fd74d18d9b33
# Parent  a1eb21f5caea4366310e32aa85248791d5bbfa0c
ui: use self._isatty() for consistency

diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -684,7 +684,7 @@ class ui(object):
                 r = default
             # sometimes self.interactive disagrees with isatty,
             # show response provided on stdin when simulating
-            if not util.isatty(self.fin):
+            if not self._isatty(self.fin):
                 self.write(r, "\n")
             return r
         except EOFError: