RequiredUseDefaults: version 0.5.5: profile: 'default/linux/amd64/17.0/musl' (180 total) failed REQUIRED_USE: exactly-one-of ( mariadb mysql )
  RequiredUseDefaults: version 0.5.6: profile: 'default/linux/amd64/17.0/musl' (158 total) failed REQUIRED_USE: exactly-one-of ( mariadb mysql )