Control.status() crashes when connecting without a host name

[joerivanruth]

The following gives a BrokenPipeError: Server closed connection.

import pymonetdb.control

# This works
ctrl = pymonetdb.control.Control(hostname='localhost', passphrase='blabla')
print(ctrl.status('demo'))

# This doesn't
ctrl = pymonetdb.control.Control(passphrase='blabla')
print(ctrl.status('demo'))

The problem was introduced by #102 COPY INTO FROM CLIENT merged in version 1.6.0.
The test suite never found it because it does pass hostname to the Control constructor.