[AVRO-2579]: Fix test by sorting fields for deterministic order

[contextshuffling]

Make sure you have checked all steps below.

Jira

• My PR addresses the following Avro Jira issues
  • https://issues.apache.org/jira/projects/AVRO/issues/AVRO-2579

Tests

• My PR adds the following unit tests OR does not need testing for this extremely good reason:
  • modifies the unit tests to make it more stable

Commits

• My commits all reference Jira issues in their subject lines

[contextshuffling]

CI failed for weird reason. The test passes locally

[Fokko]

Thanks @contextshuffling

I've restarted the CI, sometimes Travis has some intermittent issues.

[contextshuffling]

@Fokko any follow-ups on this PR?

[Fokko]

Looks like that Travis had some network issues, I've restarted the CI (again).

[contextshuffling]

Potentially related: apache/pulsar#6247

[Fokko]

Thanks @contextshuffling. Can you rebase against latest master?

[contextshuffling]

@Fokko Sorry for the late reply. should be good now

[Fokko]

We got a failing master again. Normally this doesn't happen that often, but I guess you are very unlucky @contextshuffling I'll check if I can fix master, let me get back to you.

[contextshuffling]

@Fokko I saw in the log that ImportError: cannot import name 'ContextManager'. First of all, this is in python which I do not see how my changes would touch it. After some search, this looks to be something newly added after py3.6. Is the CI image out-of-dated? Above it, the project itself builds and run all the test successfully and then the CI crashed due to this python script.

[Fokko]

@contextshuffling sorry for the late reply. Can you rebase onto master? Current master is green again.