NixOS CI job sometimes fails in Eliot test suite

[exarkun]

The NixOS CI job builds an Eliot package because Eliot isn't packaged in Nixpkgs. Our Eliot expression involves running the Eliot test suite. This is nice because it demonstrates Eliot is working as we have packaged it. However it is not nice because there is an intermittent failure in the Eliot test suite.

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FAIL: test_omitLoggerFromActionType (eliot.tests.test_validation.EndToEndValidationTests)
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Traceback (most recent call last):
  File "/tmp/nix-build-python2.7-eliot-1.7.0.drv-0/eliot-1.7.0/eliot/tests/test_validation.py", line 895, in test_omitLoggerFromActionType
    self.assertEqual(messages[0]["key"], 123)
AssertionError: 5 != 123

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This has been reported upstream - ​https://github.com/itamarst/eliot/issues/436 - but hasn't been fixed yet and may not receive much attention any time soon.

We could fix the upstream bug and update our packaging to include the fix.

We could skip the affected test when we run the Eliot test suite.

[exarkun]

​https://github.com/tahoe-lafs/tahoe-lafs/pull/680

[GitHub <noreply@…>]

In 4bf0962/trunk:

Merge pull request #680 from tahoe-lafs/3274.skip-broken-eliot-test

Skip the broken eliot test on CI

Fixes: ticket:3274