Here's an updated patch. Changes:

* Fixed what appears to have been a find/replace typo I made prior to uploading the previous patch.

* The tracebacks from the negative unit tests are now suppressed. 

* Fixed a race condition in the initializer failure handling for ThreadPoolExecutor. Futures that were submitted before the initializer actually failed will now raise a RuntimeError indicating that initializer failed.

* Suppressed an occasional queue.Full exception that would pop up while shutting down a ProcessPoolExecutor that was broken due to an initializer fail. As best as I can tell the exception is harmless, so suppressing it should be ok.

*Updated the docs.