Bump Celery to 4.2.0

[villebro]

More background can be found in celery/kombu#870, Celery needs to be fixed at 4.1.0 until Kombu 4.2.2 arrives. Fixes #5221.

[codecov-io]

Codecov Report

Merging #5222 into master will not change coverage.
The diff coverage is n/a.

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##           master    #5222   +/-   ##
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  Coverage   63.45%   63.45%           
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  Files         261      261           
  Lines       19842    19842           
  Branches     1998     1998           
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  Hits        12591    12591           
  Misses       7242     7242           
  Partials        9        9

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[john-bodley]

Packages in requirements.txt should be pinned to a specific version to help* ensure repeatability. Would you mind specifying a specific version.

• Note we actually don't include all indirect requirements from the output of pip freeze as we need this to be both Python 2 and 3 compliant and thus pin the direct package dependencies defined in setup.py.

cc: @timifasubaa

[villebro]

I removed the line regarding Kombu in requirements.txt, as I checked that it is only indirectly used via Celery. In this case one can think of Celery 4.1.1 as being broken. As Kombu isn't directly specified in setup.py, leaving it out of requirements.txt feels like the better option as per the initial comment?

[john-bodley]

@villebro so for iterating on the comment. When I tested this locally (to see if we still needed to pin kombu when using celery==4.1.0),

> pyenv version
2.7.13 (set by /Users/john_bodley/.pyenv/version)
> virtualenv env
> source env/bin/activate
> (env) pip install celery==4.1.0
...
Collecting kombu<5.0,>=4.0.2 (from celery==4.1.0)
...
> (env) pip freeze | grep kombu
kombu==4.2.1

It seems like the version of kombu might still be problematic given the range versioning defined from celery==4.1.0.

[villebro]

Oops, good call @john-bodley. I repinned Kombu at 4.1.0.

[john-bodley]

Actually @villebro they've recently released celery version 4.2.0 and I was wondering whether bumping the version higher would remedy the issue. If so we should pin celery==4.2.0 in requirements.txt and require celery>=4.2.0 in setup.py to ensure we bypass this issue.

[villebro]

Let's see what happens..

[villebro]

Looking at CI logs bumping to 4.2.0 seems to have resolved the issue!

[john-bodley]

Thanks @villebro.

[john-bodley]

For reference here’s the item in Celery 4.2.0 changelog which remedies the issue.