https://dev.azure.com/phpazuredevops/PHP/_build/results?buildId=16911&view=ms.vss-test-web.build-test-results-tab&runId=386124&resultId=100222&paneView=debug looks like a legit failure on the libmysql job. With libmysql that case now displays an error message, while the (mysqlnd) test expectation is that the error message is missing.

The newly added test also fails (https://dev.azure.com/phpazuredevops/PHP/_build/results?buildId=16911&view=ms.vss-test-web.build-test-results-tab&runId=386124&paneView=debug&resultId=100031) but that looks more like an issue with the libmysql side of things.

I addressed the libmysql side of the issue in ec56650. It's necessary to check this condition explicitly, and we were doing so inconsistently.

And fixed the other one in 671fd3f. When I initially looked at it I didn't realize that this is a libmysql-only test, so only the test expectation had to be adjusted. This fix also fixed the error message there.

Thanks @nikic