Comment 6 for bug 1835037

At Stein, the default sqlalchemy mysql driver was switched back to mysqldb; prior to stein we just used the default which was mysqldb in older releases, and pymysql from at least queens/bionic->cosmic/rocky.

The pymysql package is installed, its just that the connection URL in the nova configuration file is not using the correct pymysql+ prefix to switch to the pymysql driver.