allmydata.test.test_storage_http.HTTPTests.test_version failing on master on nixos 21.05

[exarkun]

​https://app.circleci.com/pipelines/github/tahoe-lafs/tahoe-lafs/3133/workflows/10674cae-c7c5-47bb-8635-01d11c4aa61d/jobs/63524/steps is an example build

[FAIL]
Traceback (most recent call last):
  File "/nix/store/cxddwy4pldkyvn09jhd9508jah02xhjr-python3.9-Twisted-21.7.0/lib/python3.9/site-packages/twisted/internet/defer.py", line 1661, in _inlineCallbacks
    result = current_context.run(gen.send, result)
  File "/nix/store/ilshjmwxsw7daaxbzgqca2jpbf43rhi3-python3.9-tahoe-lafs-1.16.0.post1/lib/python3.9/site-packages/allmydata/test/test_storage_http.py", line 69, in test_version
    self.assertEqual(version, expected_version)
  File "/nix/store/cxddwy4pldkyvn09jhd9508jah02xhjr-python3.9-Twisted-21.7.0/lib/python3.9/site-packages/twisted/trial/_synctest.py", line 424, in assertEqual
    super().assertEqual(first, second, msg)
  File "/nix/store/i1m8r7mv8h47wr850cdsxksy22lv6gsz-python3-3.9.6/lib/python3.9/unittest/case.py", line 831, in assertEqual
    assertion_func(first, second, msg=msg)
  File "/nix/store/i1m8r7mv8h47wr850cdsxksy22lv6gsz-python3-3.9.6/lib/python3.9/unittest/case.py", line 1130, in assertDictEqual
    self.fail(self._formatMessage(msg, standardMsg))
twisted.trial.unittest.FailTest: {b'ht[85 chars]526286848, b'maximum-mutable-share-size': 6910[280 chars]st1'} != {b'ht[85 chars]526282752, b'maximum-mutable-share-size': 6910[280 chars]st1'}
Diff is 1342 characters long. Set self.maxDiff to None to see it.

allmydata.test.test_storage_http.HTTPTests.test_version

[GitHub <noreply@…>]

In f977ce2/trunk:

Merge pull request #1164 from tahoe-lafs/3850-test-version-failure

Make the HTTP version test more robust

Fixes: ticket:3850