I'm seeing this on the attempt to update Magento 2.3.0 to 2.3.1.
There are also many messages similar to this:
Warning: Ambiguous class resolution, "PHPUnit_Framework_MockObject_Verifiable" was found in both "/home/{redacted}/domains/staging.{redacted}.com/public_html/vendor/phpunit/phpunit-mock-objects/src/Verifiable.php" and "/home/{redacted}/domains/staging.{redacted}.com/public_html/vendor/phpunit/phpunit-mock-objects/src/Framework/MockObject/Verifiable.php", the first will be used.
Can someone spell out how to safely remove whatever needs removing, from the Ubuntu 18.04 command line please?
