17.1.0 apparently breaks automat (and thus Twisted)

[mithrandi]

  File "/home/travis/build/fusionapp/entropy/.tox/py27/lib/python2.7/site-packages/xmantissa/port.py", line 52, in <module>
    from twisted.application.strports import service
  File "/home/travis/build/fusionapp/entropy/.tox/py27/lib/python2.7/site-packages/twisted/application/strports.py", line 14, in <module>
    from twisted.application.internet import StreamServerEndpointService
  File "/home/travis/build/fusionapp/entropy/.tox/py27/lib/python2.7/site-packages/twisted/application/internet.py", line 542, in <module>
    class _ClientMachine(object):
  File "/home/travis/build/fusionapp/entropy/.tox/py27/lib/python2.7/site-packages/twisted/application/internet.py", line 842, in _ClientMachine
    outputs=[_connect])
  File "/home/travis/build/fusionapp/entropy/.tox/py27/lib/python2.7/site-packages/automat/_methodical.py", line 62, in upon
    self.machine._oneTransition(self, input, enter, outputs, collector)
  File "/home/travis/build/fusionapp/entropy/.tox/py27/lib/python2.7/site-packages/automat/_methodical.py", line 255, in _oneTransition
    tuple(outputTokens))
  File "/home/travis/build/fusionapp/entropy/.tox/py27/lib/python2.7/site-packages/automat/_core.py", line 74, in addTransition
    (inState, inputSymbol, outState, tuple(outputSymbols))
exceptions.TypeError: unhashable type: 'MethodicalState'

[hynek]

cough #136 (comment)

[Tinche]

You'll have to opt into being hashable by using attr.s(hash=True) since MethodicalState is mutable. Or make it frozen, then you'll get hashability by default.

[glyph]

As the above reference shows, this is now fixed in Automat and therefore Twisted. But we should probably work out a system for compatibility testing in advance so this doesn't result in a fire drill while everyone is on planes for PyCon ;-). Thanks very much to @markrwilliams for the SUPER rapid response fix & release.

[hynek]

Yay Mark! 🎉

Also yay software that's always ready for release.

[mithrandi]

Closing this since automat is fixed and it seems like this isn't an attrs bug insofar as the compat break was deliberate.