There are two ebuilds that issue this warning when emerging: Sorry, but {binutils|gdb} does not support the LINGUAs: en I have LINGUAS="en de". I've got the strong suspicion that these two tools have hardwired english support and therefore don't have a matching configuration option. Still, the message is slightly annoying to experienced users, especially with elog, and probably rather confusing to novice users. Bug 183176 was just such a case, a user who got confused by this warning. I would suggest that an ebuild can provide a list of built-in linguas, which are stripped silently by strip-linguas in eutils.eclass, to avoid these warnings. An environment variable to contain this list might be the easiest approach.
Completely harmless warning.
> Completely harmless warning. I disagree with the closing of this bug so off-handedly. This kind of issue makes Gentoo look like the red-neck neighbor with his rusty pickup out in the front lawn on cinder blocks. But yeah.... It's completely harmless.