Ticket #16023: 16023.diff

wp-includes/l10n.php

@@ -32 +32 @@
                 return apply_filters( 'locale', $locale );
 
         // WPLANG is defined in wp-config.
-        if ( defined( 'WPLANG' ) )
+        if ( defined( 'WPLANG' ) ) {
                 $locale = WPLANG;
+                if ( 2 == strlen( $locale ) )
+                        $locale = strtolower( $locale ) . '_' . strtoupper( $locale );
+        }
 
         // If multisite, check options.
         if ( is_multisite() && !defined('WP_INSTALLING') ) {