From 60ed8525b01436d92adb726e97e0c2cbe556d859 Mon Sep 17 00:00:00 2001
From: David Wilson <dw@botanicus.net>
Date: Fri, 22 Sep 2017 13:39:20 +0530
Subject: [PATCH] Fix inverted logic.

---
 mitogen/master.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mitogen/master.py b/mitogen/master.py
index 7b7c0ff1..f20e07e9 100644
--- a/mitogen/master.py
+++ b/mitogen/master.py
@@ -388,7 +388,7 @@ class ModuleFinder(object):
         module to be loaded that is not part of the standard library.
         """
         related = self._related_cache.get(fullname)
-        if related is None:
+        if related is not None:
             return related
 
         _, src, _ = self.get_module_source(fullname)