Index: wp-admin/includes/plugin-install.php
===================================================================
--- wp-admin/includes/plugin-install.php	(revision 28967)
+++ wp-admin/includes/plugin-install.php	(working copy)
@@ -34,6 +34,9 @@
 	if ( !isset($args->per_page) )
 		$args->per_page = 24;
 
+	if ( !isset($args->locale) )
+		$args->locale = get_locale();
+
 	/**
 	 * Override the Plugin Install API arguments.
 	 *