From 8f697b4903722308c710c4c5d2060238db50f968 Mon Sep 17 00:00:00 2001
From: Ben Darnell <ben@bendarnell.com>
Date: Wed, 29 Jul 2015 23:02:42 -0400
Subject: [PATCH] Correctly clear IOLoop.current() after TwistedIOLoop exits.

---
 tornado/platform/twisted.py | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/tornado/platform/twisted.py b/tornado/platform/twisted.py
index 7b3c8ca5e..0bb8d54fe 100644
--- a/tornado/platform/twisted.py
+++ b/tornado/platform/twisted.py
@@ -477,8 +477,15 @@ class TwistedIOLoop(tornado.ioloop.IOLoop):
         del self.fds[fd]
 
     def start(self):
-        self._setup_logging()
-        self.reactor.run()
+        old_current = IOLoop.current(instance=False)
+        try:
+            self._setup_logging()
+            self.reactor.run()
+        finally:
+            if old_current is None:
+                IOLoop.clear_current()
+            else:
+                old_current.make_current()
 
     def stop(self):
         self.reactor.crash()
-- 
2.47.2