subunit2junitxml fails to output subunit stream

[Thomi Richards]

We occaisonally encounter a problem with subunit2junitxml.

When we run our tests, we create a subunit (v2) result file, and then later run:

$ cat test_results.subunit | subunit2junitxml > test_results.xml

Most of the time this works fine, but occaisonally it crashes with the following stack trace:

Traceback (most recent call last):
  File "/usr/bin/subunit2junitxml", line 36, in <module>
    protocol_version=2)
  File "/usr/lib/python3/dist-packages/subunit/filters.py", line 177, in run_filter_script
    options.forward, protocol_version=protocol_version)
  File "/usr/lib/python3/dist-packages/subunit/filters.py", line 150, in filter_by_result
    protocol_version=protocol_version)
  File "/usr/lib/python3/dist-packages/subunit/filters.py", line 105, in run_tests_from_stream
    result.stopTestRun()
  File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 491, in stopTestRun
    sink.stopTestRun()
  File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 1449, in stopTestRun
    self.decorated.stopTestRun()
  File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 1265, in stopTestRun
    return self.decorated.stopTestRun()
  File "/usr/lib/python3/dist-packages/junitxml/__init__.py", line 169, in stopTestRun
    self._stream.write(''.join(self._results))
UnicodeEncodeError: 'ascii' codec can't encode character '\xa2' in position 3062: ordinal not in range(128)

The subunit file responsible for that crash is attached to the bug report, but I'm unable to reproduce the crash locally.

[Robert Collins (lifeless)]

The error is in transcoding - which we should be avoiding // not triggering