Merge remote-tracking branch 'alekstorm/template_trace' into merge

Conflicts:
	tornado/template.py

diff --cc tornado/template.py
index fc9563016ac4e55a30a957ddbe2e7b1cccaf7f8a,5d8993ba2a83f67571fe1e29e67d2e7948b8792a..fda7e5fdfedb728d123b95f69755e91409de6f2c
--- 1/tornado/template.py
--- 2/tornado/template.py
+++ b/tornado/template.py
@@@ -177,7 -177,8 +177,9 @@@ import loggin
  import os.path
  import posixpath
  import re
 +import threading
+ import sys
+ import traceback
  
  from tornado import escape
  from tornado.util import bytes_type

diff --cc tornado/testing.py
Simple merge