Revert "Bump mysqlclient to 2.0.1 (#9987)"

[potiuk]

This reverts commit c438812.

Seems that mysql upgrade caused a problem with missing _mysql_exceptions. Let's revert before we investigate and fix.

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[potiuk]

Explanation: the problem is @kaxil that in the regular PR runs there is no "eager upgrade" performed, so just changing the upper bound will not make the dependency to be upgraded to latest version in the PR.

This is in order to make sure we are not hit in PRs by the external dependency upgrade problems we used to have. It's only the master merges that perform "eager upgrade" and run tests on the latest versions of requirements - this way we have a chance to react before all PRs are affected. So the "early warning" worked in this case in fact (other's PR would be unaffected as they would still be using the "constrained" version of mysql which is still 1.3.14 - it's only master build that was affected). Also since the master build failed- the constraints would not be upgraded, which is exactly what is expected :).

In order to actually test the latest version locally you need to enter breeze and run:

pip install --upgrade mysqlclient and run tests after that or simply push the change you want to test to your local fork as master.

[kaxil]

Explanation: the problem is @kaxil that in the regular PR runs there is no "eager upgrade" performed, so just changing the upper bound will not make the dependency to be upgraded to latest version in the PR.

This is in order to make sure we are not hit in PRs by the external dependency upgrade problems we used to have. It's only the master merges that perform "eager upgrade" and run tests on the latest versions of requirements - this way we have a chance to react before all PRs are affected. So the "early warning" worked in this case in fact (other's PR would be unaffected as they would still be using the "constrained" version of mysql which is still 1.3.14 - it's only master build that was affected). Also since the master build failed- the constraints would not be upgraded, which is exactly what is expected :).

In order to actually test the latest version locally you need to enter breeze and run:

pip install --upgrade mysqlclient and run tests after that or simply push the change you want to test to your local fork as master.

Got it, thanks :)