Yocto Fido

I am trying to use PREFERRED_VERSION to select an earlier version
of the "db" package. The build includes both db and db-native variants
of the package.

I set PREFERRED_VERSION_db variable and this successfully changes
the version of the db package but not the db-native package.

I tried also setting PREFERRED_VERSION_db-native but this doesn't
seem to have any effect.

What am I missing? How can I override version for a native package?