Unable to migrate from MySQL due to incorrect definition of table mysql.proc and mysql.event

After installation MySQL and initialization its data directory using mysql_install_db, I removed MySQL packages and installed MariaDB counterparts. Then I ran MariaDB's mysql_install_db again, but scripts threw out that mysql.proc and mysql.event have incorrect definitions (full log in attachment).

I'm aware that I should run mysql_upgrade first and do not run mysql_install_db second time, but I want to make migration straighforward for Arch users. As far as I know there is no safe and sure way to check if calling the script is required. MariaDB's mysql_install_db worked fine until 5.5.28 release, and now user have to intervene manually. (However clean MariaDB installs are working fine.)

I wouldn't even report that, but you "advertise" that as long as MySQL and Maria have same base version, the migration should be flawless. If you won't fix this obvious regression, it will make Arch migration to MariaDB much slower.