Fix/dbt deps retry none answer

[b-per]

Allow retries when the answer received after a dbt deps is None

resolves #4178

Description

Add the logic to handle the case when the answer received is None.
I picked the requests exception InvalidJSONError to handle the situation but I am not sure if another one would be more suitable.

I didn't add tests and wouldn't be too sure where to start if a test would need to be created. Happy to add one if it is required.

Checklist

• I have signed the CLA
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• I have updated the CHANGELOG.md and added information about my change

[jtcohen6]

Thanks for the contribution @b-per! This looks great to me. I'll look to see if there's an easy place to add a test, but by itself the code is probably good to go.

[jtcohen6]

Just a few small things from flake8 + mypy:

core/dbt/utils.py:618:100: E501 line too long (123 > 99 characters)
core/dbt/clients/registry.py:34:100: E501 line too long (104 > 99 characters)

core/dbt/utils.py:618: error: Module has no attribute "InvalidJSONError"

I didn't add tests and wouldn't be too sure where to start if a test would need to be created. Happy to add one if it is required.

I think you could add a test to test/unit/test_core_dbt_utils.py, which was the test added in #3729. Something like:

    def test_connection_exception_retry_success(self):
        Counter._reset()
        connection_exception_retry(lambda: Counter._add_with_none_exception(), 5)
        self.assertEqual(2, counter) # 2 = original attempt returned None, plus 1 retry

class Counter():
    ...
    def _add_with_none_exception():
        global counter
        counter+=1
        if counter < 2:
            raise requests.exceptions.InvalidJSONError

If you have a chance to do that today, great! If not, I'll try to get this merged ahead of v1.0.0-rc1, which we're planning to cut very soon.

[b-per]

Thanks for the review @jtcohen6

I am not too sure why InvalidJSONError raises an error with mypy, the class exists in exceptions.py.

Looking at the other exceptions available I actually changed the one raised to ContentDecodingError which doesn't raise a mypy error.

[jtcohen6]

@b-per I'm not sure why mypy raised that error either. It looks like InvalidJSONError was just added in v2.6.0, but that is indeed the version of requests installed in CI.

In any case, thanks for the quick follow-up! This is good to go