title: PyDev (Eclipse) unhandled exception: 'NoneType' object has no attribute 'pydev_notify_kill'
body: <p>For a few hours now PyDev (installed inside Eclipse) throws some weird error at me:</p>
  
  <pre><code>Unhandled exception in thread started by &lt;_pydev_bundle.pydev_monkey._NewThreadStartupWithTrace instance at 0x0423E918&gt;
  27.06.2018 04:44:34 ERROR     &lt;&lt;&lt; UNCAUGHT EXCEPTION &gt;&gt;&gt;
  Traceback (most recent call last):
    File "C:\Users\...\.p2\pool\plugins\org.python.pydev.core_6.4.1.201806231219\pysrc\_pydev_bundle\pydev_monkey.py", line 617, in __call__
      global_debugger.notify_thread_created(thread_id, t)
    File "C:\Users\...\.p2\pool\plugins\org.python.pydev.core_6.4.1.201806231219\pysrc\pydevd.py", line 467, in notify_thread_created
      elif thread.additional_info.pydev_notify_kill:
  AttributeError: 'NoneType' object has no attribute 'pydev_notify_kill'
  </code></pre>
  
  <p>I am debugging <a href="https://github.com/GammaC0de/pyload/tree/captcha-interactive" rel="nofollow noreferrer">pyLoad</a> and I get this error and stack trace exactly when <a href="https://github.com/GammaC0de/pyload/blob/captcha-interactive/module/database/DatabaseBackend.py#L125" rel="nofollow noreferrer">this line</a> is executed. By inspecting the PyDev sources I found out that it has something to do with threads. Apparently PyDev tries to catch the creation of the new thread and start tracing it - but something in this proccess seems to go south.</p>
  
  <p>Everything was working just fine a few hours ago, right before a few Python packages were striking and I had to reinstall my whole Python runtime and after that did several Eclipse and PyDev re-installations.</p>
  
  <p>I'm using the latest Eclipse Oxygen.3A and PyDev 6.4.1.201806231219. I had my Eclipse/PyDev setup running stable for at least 2-2.5 years now so I can't really tell whether I had a similar problem back then and resolved it somehow. But right now I'm really lost and I hope one of you has any good idea on what could cause this. Maybe some simple setting of PyDev?</p>
  
  <p>Any help is very much appreciated!</p>