See tracker.
+ 18 Aug 2013; Mikle Kolyada <zlogene@gentoo.org> -DBD-mysql-4.01.7.ebuild: + drop old wrt bug #478750 +
dependency.bad 6 dev-db/mysql/mysql-5.1.66.ebuild: PDEPEND: s390(default/linux/s390/13.0) ['>=dev-perl/DBD-mysql-2.9004'] dev-db/mysql/mysql-5.1.66.ebuild: PDEPEND: s390(default/linux/s390/13.0/s390x) ['>=dev-perl/DBD-mysql-2.9004'] dev-db/mysql/mysql-5.1.67.ebuild: PDEPEND: s390(default/linux/s390/13.0) ['>=dev-perl/DBD-mysql-2.9004'] dev-db/mysql/mysql-5.1.67.ebuild: PDEPEND: s390(default/linux/s390/13.0/s390x) ['>=dev-perl/DBD-mysql-2.9004'] dev-db/mysql/mysql-5.1.70.ebuild: PDEPEND: s390(default/linux/s390/13.0) ['>=dev-perl/DBD-mysql-2.9004'] dev-db/mysql/mysql-5.1.70.ebuild: PDEPEND: s390(default/linux/s390/13.0/s390x) ['>=dev-perl/DBD-mysql-2.9004'] Nope. Stable a different version for s390 first. Restored that version to make repoman happy.
Oops, it has sh stable keyword too, and should be stable. Sorry for that :/
done now.