Admin scripts (such as mysql_setpermission) provided by MySQL require
dev-perl/DBI to run.
It actually depends upon dev-perl/DBD-mysql, which itself depends
upon dev-perl/DBI and dev-db/mysql; a circular dependency. I guess people
should install dev-perl/DBD-mysql after they install mysql.. :/
I didn't find how RDEPEND is managed by ebuild but if dev-perl/DBI is in the
running dependencies and not in the compile dependencies, it could be emerged
AFTER mysql is emerged and it would prevent circular dependency.