exit celery with non zero exit value if failing

[tned73]

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Description

There is an issue with version 5.x for the celery command. If the command is failing, the exit value is still 0. This PR will fix this and exits with the intended exit value.

NOTE: All patches should be made against master, not a maintenance branch like
3.1, 2.5, etc. That is unless the bug is already fixed in master, but not in
that version series.

If it fixes a bug or resolves a feature request,
be sure to link to that issue via (Fixes #6601) for example.
-->

[lgtm-com]

This pull request fixes 2 alerts when merging 2f5758f into 855d551 - view on LGTM.com

fixed alerts:

• 1 for Non-exception in 'except' clause
• 1 for Module is imported with 'import' and 'import from'

[thedrow]

We don't need a specialized exception.
We can simply use ctx.fail().

[tned73]

If I look at ctx.fail() it has a message parameter and not a exit value parameter. Using this will solve a part of the issue. It will probably exit with value 1 and not the 69 if the celery inspect ping fails as version 4.x does.
for my purposes it is not an issue.

please advice on direction to solve this issue

[thedrow]

Huh.
That API is very surprising.

I think we're good to go on this one.

[thedrow]

LGTM

[thedrow]

LGTM

[auvipy]

Looks good. should we merge this as is or need unit test?

[thedrow]

There are no unit tests for the CLI at the time being, unfortunately.
I don't have time to write them, currently.