--- a/hgext/extdiff.py	Sat Nov 08 12:57:42 2014 +0900
+++ b/hgext/extdiff.py	Sat Nov 08 13:06:22 2014 +0900
@@ -226,7 +226,7 @@
         cmdline = util.shellquote(diffcmd) + ' ' + args
 
         ui.debug('running %r in %s\n' % (cmdline, tmproot))
-        util.system(cmdline, cwd=tmproot, out=ui.fout)
+        ui.system(cmdline, cwd=tmproot)
 
         for copy_fn, working_fn, mtime in fns_and_mtime:
             if os.lstat(copy_fn).st_mtime != mtime: