Fix --debug_gc option on python 3.

diff --git a/tornado/test/runtests.py b/tornado/test/runtests.py
index 2c8bb1db9c6b59a91cb9d849eae903a27f77be7e..786bbf9831f0540089f6bacf64add8ee78e4de49 100644 (file)
--- a/tornado/test/runtests.py
+++ b/tornado/test/runtests.py
@@ -13,6 +13,11 @@ from tornado.netutil import Resolver
 from tornado.options import define, options, add_parse_callback
 from tornado.test.util import unittest
 
+try:
+    reduce  # py2
+except NameError:
+    from functools import reduce  # py3
+
 TEST_MODULES = [
     'tornado.httputil.doctests',
     'tornado.iostream.doctests',