[FTBFS] salt: build hangs running dh_auto_test

[Iain Buclaw]

After applying fix for #1809452, #1819254 and #1819258.

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[CPU:0.0%|MEM:28.8%] ... 12:37:59,469 [asyncio :1274][ERROR ] Future exception was never retrieved
future: <Future finished exception=TypeError("__init__() got an unexpected keyword argument 'io_loop'",)>
Traceback (most recent call last):
  File "/usr/lib/python3/dist-packages/tornado/gen.py", line 315, in wrapper
    yielded = next(result)
  File "/home/ibuclaw/src/salt/salt-2017.7.4+dfsg1/salt/transport/ipc.py", line 335, in _connect
    io_loop=self.io_loop,
  File "/usr/lib/python3/dist-packages/tornado/iostream.py", line 1169, in __init__
    super(IOStream, self).__init__(*args, **kwargs)
TypeError: __init__() got an unexpected keyword argument 'io_loop'
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Then gets stuck in an infinite loop.

[Benjamin Drung (bdrung)]

This test failure is fixed in salt 2018.3.3+dfsg1-1 and therefore since Ubuntu 19.04.