diff -r 277f4fe6d01a -r 39d13b8c101d mercurial/util.py
--- a/mercurial/util.py	Thu Oct 20 23:40:24 2016 +0900
+++ b/mercurial/util.py	Thu Oct 20 23:53:36 2016 +0900
@@ -986,7 +986,7 @@
     if environ is None:
         environ = {}
     try:
-        sys.stdout.flush()
+        stdout.flush()
     except Exception:
         pass
     def py2shell(val):
@@ -2759,9 +2759,9 @@
         finally:
             elapsed = time.time() - start
             _timenesting[0] -= indent
-            sys.stderr.write('%s%s: %s\n' %
-                             (' ' * _timenesting[0], func.__name__,
-                              timecount(elapsed)))
+            stderr.write('%s%s: %s\n' %
+                         (' ' * _timenesting[0], func.__name__,
+                          timecount(elapsed)))
     return wrapper
 
 _sizeunits = (('m', 2**20), ('k', 2**10), ('g', 2**30),
@@ -2826,7 +2826,7 @@
             else:
                 yield line % (fnmax, fnln, func)
 
-def debugstacktrace(msg='stacktrace', skip=0, f=sys.stderr, otherf=sys.stdout):
+def debugstacktrace(msg='stacktrace', skip=0, f=stderr, otherf=stdout):
     '''Writes a message to f (stderr) with a nicely formatted stacktrace.
     Skips the 'skip' last entries. By default it will flush stdout first.
     It can be used everywhere and intentionally does not require an ui object.