bandwidth_file test_version_position fails on python 3

  descriptor.bandwidth_file...                         failed (0.02s)
test_content_example                                   0 ms  [SUCCESS]
test_format_v1_0                                       3 ms  [SUCCESS]
test_format_v1_2                                       3 ms  [SUCCESS]
test_from_str                                          0 ms  [SUCCESS]
test_header_alternate_div                              2 ms  [SUCCESS]
test_header_for_v1                                     0 ms  [SUCCESS]
test_invalid_timestamp                                 1 ms  [SUCCESS]
test_minimal_bandwidth_file                            0 ms  [SUCCESS]
test_new_header_attribute                              0 ms  [SUCCESS]
test_version_position                                        [FAILURE]
======================================================================
FAIL: test_version_position
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/travis/build/teor2345/stem/test/unit/descriptor/bandwidth_file.py", line 215, in test_version_position
    self.assertEqual(RIGHT_VERSION_POSITION, content)
AssertionError: '1410723598\nversion=1.1.0\nfile_created=2019-01-14T05:35:06\n=====' != b'1410723598\nversion=1.1.0\nfile_created=2019-01-14T05:35:06\n====='
----------------------------------------------------------------------
Ran 10 tests in 0.014s
FAILED (failures=1)

https://travis-ci.org/teor2345/stem/jobs/536613177#L1463

Looks like bytes/string confusion to me.

This error happens on python 3.6 and 3.7, and pypy 3.5. The python 3.8 builds fail before this test.