Comment 0 for bug 1809809

Running subunit2junitxml with python3 fails:
[zuul@fedora-28-rdo-cloud-0000000003 ~]$ subunit2junitxml /home/zuul/tempest/testrepository.subunit --output-to /home/zuul/tempest/tempest.xml
Traceback (most recent call last):
  File "/usr/bin/subunit2junitxml", line 36, in <module>
    protocol_version=2)
  File "/usr/lib/python3.6/site-packages/subunit/filters.py", line 183, in run_filter_script
    input_stream=find_stream(sys.stdin, args))
  File "/usr/lib/python3.6/site-packages/subunit/filters.py", line 146, in filter_by_result
    output_to = file(output_path, 'wb')
NameError: name 'file' is not defined