I tried to update ant-core on a system running stable x86 but with migration overlay available. # emerge -pv1 ant-core !!! All ebuilds that could satisfy ">=dev-java/java-config-2.0.19-r1" have been masked. !!! One of the following masked packages is required to complete your request: - dev-java/java-config-2.0.21 (masked by: ~x86 keyword) !!! (dependency required by "dev-java/ant-core-1.6.2-r15" [ebuild]) Unfortunately there seems to be no trac component for migration overlay. And I'm not sure what you manage in trac and what here in bugzilla. karltk asked me to file a bug for this.
OK, I know learned about E_DEPEND, so the dependency from the java-pkg-2.eclass gets propagated. So probably no ebuild using these second generation eclasses should be marked stable before java-config-2 is stabilized. So maybe ant-core simply should be ~x86.
I forgot to to fix the keywords when I did the bump. Sorry bout that.