diff -r d9d8d2e0f701 -r 41c03b7592ed mercurial/hook.py
--- a/mercurial/hook.py	Sat Nov 08 12:57:42 2014 +0900
+++ b/mercurial/hook.py	Sat Nov 08 13:06:22 2014 +0900
@@ -131,7 +131,7 @@
         cwd = repo.root
     else:
         cwd = os.getcwd()
-    r = util.system(cmd, environ=env, cwd=cwd, out=ui.fout)
+    r = ui.system(cmd, environ=env, cwd=cwd)
 
     duration = time.time() - starttime
     ui.log('exthook', 'exthook-%s: %s finished in %0.2f seconds\n',