Improved debug

Not working without it.
```
Exception in thread Manhole:
Traceback (most recent call last):
  File "/opt/pypy3/lib-python/3/threading.py", line 740, in _bootstrap_inner
    self.run()
  File "/home/mdevaev/.local/lib/python3.2/site-packages/manhole.py", line 186, in run
    sock = self.get_socket()
TypeError: get_socket() takes no arguments (1 given)
```