Some weird test output on 3.5

I see this on linux w/ our 3.5 EDM runtimes:

```
...................................................................../home/vagrant/.edm-build/envs/build-env/lib/python3.5/site-packages/encore/events/event_manager.py:446: DeprecationWarning: The 'warn' method is deprecated, use 'warning' instead
traceback.format_exc()))
Exception i'm just like this occurred in listener: for event: :
Traceback (most recent call last):
File "/home/vagrant/.edm-build/envs/build-env/lib/python3.5/site-packages/encore/events/event_manager.py", line 442, in emit
listener(event)
File "/home/vagrant/.edm-build/envs/build-env/lib/python3.5/site-packages/mock/mock.py", line 1062, in __call__
return _mock_self._mock_call(*args, **kwargs)
File "/home/vagrant/.edm-build/envs/build-env/lib/python3.5/site-packages/mock/mock.py", line 1132, in _mock_call
return self._mock_wraps(*args, **kwargs)
File "/home/vagrant/.edm-build/envs/build-env/lib/python3.5/site-packages/encore/events/tests/test_event_manager.py", line 53, in callback3
raise RuntimeError('i\'m just like this')
RuntimeError: i'm just like this

..Exception you did it occurred in listener: for event: .MyEvt object at 0x2ada31a222b0>:
Traceback (most recent call last):
File "/home/vagrant/.edm-build/envs/build-env/lib/python3.5/site-packages/encore/events/event_manager.py", line 442, in emit
listener(event)
File "/home/vagrant/.edm-build/envs/build-env/lib/python3.5/site-packages/mock/mock.py", line 1062, in __call__
return _mock_self._mock_call(*args, **kwargs)
File "/home/vagrant/.edm-build/envs/build-env/lib/python3.5/site-packages/mock/mock.py", line 1132, in _mock_call
return self._mock_wraps(*args, **kwargs)
File "/home/vagrant/.edm-build/envs/build-env/lib/python3.5/site-packages/encore/events/tests/test_event_manager.py", line 277, in callback
raise Exception('you did it')
Exception: you did it
```

No errors, but that looks a bit weird.