make.defaults, use.force, use.mask, package.use, package.use.force and package.use.mask placed directly in ${repository_path}/profiles should be supported. They would affect only ebuilds from given repository.
Additionally this feature should affect use.stable.force, use.stable.mask, package.use.stable.force and package.use.stable.mask.
Portage commits: http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=96ab7b436ceb3543f5158aab1fab48470c3f0b98 http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=9838a00a264c90faf8040e923096136a1c022247 http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=ba059b888a124269df460f82ef8b30f269dd3c50 http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=1fdeb78d08bac14f3f999f112499d179a87cf342 http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=33b197b02574c0f49d4dce659562d2f3362e5eba http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=96ab3f8e703138bbbda0c50bb05998281207a4d4 http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=c3f0895fb89c7b0647428de37eb0f893939d93f7 http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=84f53ead91047d1389c80edeb7d9d1720e07e2a4 http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=fa9e85bbe7c513193756a2d13ce63a609138753d http://git.overlays.gentoo.org/gitweb/?p=proj/portage.git;a=commit;h=87c9660406126e19a29531d4e7ab0d70f1dbb3e3
I need to append USE_EXPAND in my overlay, but unable to do so before this enhancement is implemented.