From dc1d1d4e8168715d4948b4e47ad4148eb7884f92 2015-11-26 23:05:44
From: Min RK <benjaminrk@gmail.com>
Date: 2015-11-26 23:05:44
Subject: [PATCH] remove unregister trait-change callback in ExtensionManager.__del__

Due to reference cycles, this can never be called at a time when it would matter,
but seems to cause weird crashes sometimes during interpreter teardown on Python 3.5 with traitlets 4.1.
---

diff --git a/IPython/core/extensions.py b/IPython/core/extensions.py
index f31dd83..cd1dd59 100644
--- a/IPython/core/extensions.py
+++ b/IPython/core/extensions.py
@@ -59,11 +59,6 @@ class ExtensionManager(Configurable):
         )
         self.loaded = set()
 
-    def __del__(self):
-        self.shell.on_trait_change(
-            self._on_ipython_dir_changed, 'ipython_dir', remove=True
-        )
-
     @property
     def ipython_extension_dir(self):
         return os.path.join(self.shell.ipython_dir, u'extensions')