Yoast/wordpress-seo — pull request #1017 by maiis (2014-04-14 22:09:38+00:00)
Title: Better OG locale

I ran into a case for a client using the locale es_PE in wordpress, and as it's not recognized by facebook, the OG meta was set to en_US.

With the fix it's now setting es_ES which looks more appropriate. Correct me if i'm wrong.
The best one would be es_LA, but it's corner case i guess.