autopilot crash possibly preventing all of filemanager tests from being run on the dashboard

[Chris Gagnon]

https://jenkins.qa.ubuntu.com/job/vivid-touch-mako-smoke-daily/122/artifact/clientlogs/filemanager/_usr_bin_autopilot3.32011.crash/*view*/

Traceback:
 Traceback (most recent call last):
   File "/usr/bin/autopilot3", line 9, in <module>
     load_entry_point('autopilot==1.5.0', 'console_scripts', 'autopilot3')()
   File "/usr/lib/python3/dist-packages/autopilot/run.py", line 742, in main
     test_app.run()
   File "/usr/lib/python3/dist-packages/autopilot/run.py", line 628, in run
     action()
   File "/usr/lib/python3/dist-packages/autopilot/run.py", line 694, in run_tests
     test_result = test_suite.run(result)
   File "/usr/lib/python3.4/unittest/suite.py", line 125, in run
     test(result)
   File "/usr/lib/python3.4/unittest/case.py", line 625, in __call__
     return self.run(*args, **kwds)
   File "/usr/lib/python3/dist-packages/testscenarios/testcase.py", line 65, in run
     return super(WithScenarios, self).run(result)
   File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 585, in run
     return self.__RunTest(self, self.exception_handlers).run(result)
   File "/usr/lib/python3/dist-packages/autopilot/testcase.py", line 132, in run
     return super().run(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/testtools/runtest.py", line 74, in run
     return self._run_one(actual_result)
   File "/usr/lib/python3/dist-packages/testtools/runtest.py", line 88, in _run_one
     return self._run_prepared_result(ExtendedToOriginalDecorator(result))
   File "/usr/lib/python3/dist-packages/testtools/runtest.py", line 107, in _run_prepared_result
     handler(self.case, self.result, e)
   File "/usr/lib/python3/dist-packages/testtools/testcase.py", line 558, in _report_failure
     result.addFailure(self, details=self.getDetails())
   File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 1149, in addFailure
     return self.decorated.addFailure(test, err)
   File "/usr/lib/python3/dist-packages/autopilot/testresult.py", line 78, in addFailure
     return super(type(self), self).addFailure(test, err, details)
   File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 1546, in addFailure
     return self.decorated.addFailure(test, err, details=details)
   File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 1322, in addError
     self._convert(test, err, details, 'fail')
   File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 1350, in _convert
     test_tags=self.current_tags, timestamp=now)
   File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 408, in status
     super(CopyStreamResult, self).status(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 649, in status
     self.on_test(self._inprogress.pop(key))
   File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 742, in _gather_test
     self._handle_status[test_dict['status']](case)
   File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 761, in _fail
     message = _details_to_str(case._details, special="traceback")
   File "/usr/lib/python3/dist-packages/testtools/testresult/real.py", line 1752, in _details_to_str
     text = content.as_text().strip()
   File "/usr/lib/python3/dist-packages/testtools/content.py", line 94, in as_text
     return _u('').join(self.iter_text())
   File "/usr/lib/python3/dist-packages/testtools/content.py", line 118, in _iter_text
     yield decoder.decode(bytes)
   File "/usr/lib/python3.4/encodings/latin_1.py", line 26, in decode
     return codecs.latin_1_decode(input,self.errors)[0]
 TypeError: 'NoneType' does not support the buffer interface
UserGroups: adm autopilot cdrom dialout dip plugdev sudo tty video
_LogindSession: /user.slice/user-0.slice/session-c2.scope