From 9e6b66c499173a0523ef933a122b1a71801b0dfd Mon Sep 17 00:00:00 2001
From: "A. Jesse Jiryu Davis" <jesse@mongodb.com>
Date: Sat, 30 Jan 2016 12:51:51 -0500
Subject: [PATCH] PYTHON-1050 Rare RuntimeError during shutdown.

---
 pymongo/periodic_executor.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pymongo/periodic_executor.py b/pymongo/periodic_executor.py
index 8b7015b3f..68add5ed4 100644
--- a/pymongo/periodic_executor.py
+++ b/pymongo/periodic_executor.py
@@ -79,8 +79,8 @@ class PeriodicExecutor(object):
         if self._thread is not None:
             try:
                 self._thread.join(timeout)
-            except ReferenceError:
-                # Thread already terminated.
+            except (ReferenceError, RuntimeError):
+                # Thread already terminated, or not yet started.
                 pass
 
     def wake(self):