Starting from mysql version 8 it's not possible to create a user
implictly when using GRANT.
This patch makes the behavior compatible with that.
Change-Id: Id92a73ffc98906f30cadee98650e86d4d080653b
Co-written-by: Riccardo Pittau <elfosardo@gmail.com>
Signed-off-by: Sean McGinnis <sean.mcginnis@gmail.com>