Bug 394155

Also seen when installing for example graphite-carbon. Typical traceback:

>   File "/usr/lib/python2.7/dist-packages/carbon/service.py", line 18, in <module>
>     from twisted.application.internet import TCPServer, TCPClient, UDPServer
>   File "/usr/lib/python2.7/dist-packages/twisted/application/internet.py", line 54, in <module>
>     from automat import MethodicalMachine
>   File "/usr/lib/python2.7/dist-packages/automat/__init__.py", line 2, in <module>
>     from ._methodical import MethodicalMachine
>   File "/usr/lib/python2.7/dist-packages/automat/_methodical.py", line 34, in <module>
>     @attr.s(frozen=True)
> exceptions.TypeError: attributes() got an unexpected keyword argument 'frozen'

The root cause seems to be one step away from Twisted: python-twisted-code 17.9.0 depends python-automat>=0.6.0 depends python-attr, it's the latter which is broken. Twisted 16.x from xenial doesn't depend on automat at all, hence it escapes.

https://github.com/glyph/automat/issues/65 describes the issue:
> The patch for #62 in 3766391 that passes the frozen keyword to attr.s assumes attrs>=16.1.0 per python-attrs/attrs@cfa6d2e.

The initial patch for #62 made it into automat-0.6.0 (a year ago) but the fix in https://github.com/glyph/automat/pull/66 didn't, and there's been no point release since: https://github.com/glyph/automat/releases

My local workaround for now has been to downgrade Twisted to 16.0.0-1ubuntu0.2 (from xenial repo) and hold them.

This ticket has been archived due to the age of this request, in order to keep currently present issues at the forefront for proper resolution. If this issue is still present, please reopen this ticket and provide additional details related to the request.