Test failure accessing nonexistent object

[sewnie]

Exception ignored in atexit callback: <function Halo.__init__.<locals>.clean_up at 0x77e901426700>
Traceback (most recent call last):
  File "/builddir/python-halo-0.0.31/halo/halo.py", line 104, in clean_up
    self.stop()
  File "/builddir/python-halo-0.0.31/halo/halo.py", line 515, in stop
    self.clear()
  File "/builddir/python-halo-0.0.31/halo/halo_notebook.py", line 51, in clear
    with self.output:
         ^^^^^^^^^^^
AttributeError: 'HaloNotebook' object has no attribute 'output'