This was never an issue because each ebuild always contained at least ruby18 in USE_RUBY, but this assumption is no longer safe. People may eselect ruby19 and find old packages that are not yet marked for ruby19. Also, in the future we will see packages that no longer work on ruby18. Perhaps we should enforce that a package can only be built with an eselected ruby that it also in USE_RUBY? This bug was triggered by https://bugs.gentoo.org/show_bug.cgi?id=395657#c9
*** Bug 540154 has been marked as a duplicate of this bug. ***
*** Bug 809617 has been marked as a duplicate of this bug. ***
*** Bug 809215 has been marked as a duplicate of this bug. ***