Hamelin-net produces an error when receiving an EOF

`Exception in thread server-thread-[grep]:
Traceback (most recent call last):
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py", line 810, in __bootstrap_inner
self.run()
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/threading.py", line 763, in run
self.__target(*self.__args, **self.__kwargs)
File "/Users/Macbook_2/Downloads/hamelin-master 5/hamelin-py/bin/hamelin.py", line 90, in event_loop
self.handle_quit(poll)
File "/Users/Macbook_2/Downloads/hamelin-master 5/hamelin-py/bin/hamelin-net", line 39, in quit
conn.shutdown(socket.SHUT_RDWR)
File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/socket.py", line 224, in meth
return getattr(self._sock,name)(*args)
error: [Errno 57] Socket is not connected`

Latest from master as of this posting with Python 2.7.8 (v2.7.8:ee879c0ffa11, Jun 29 2014, 21:07:35) and I don't know what version of netcat on Mac OS 10.10 Yosemite.

Hamelin continues to work fine after displaying the error message, and it doesn't stop the program from running.

Start in bin/hamelin-net at the quit function referenced by the traceback, and trace how event_loop handles an EOF. Reproduce the disconnect with the reported Python 2.7 and netcat setup if available. Done means receiving EOF no longer prints the socket-not-connected traceback while Hamelin continues running.

Written by the indexing model from the issue text.