[Fixed in next Release] Wrong language code for AJAX POST requests if POST contains

Background of the issue:
open wp-admin (e.g. your admin language is "fr")
Click something that will trigger an admin-ajax POST request that contains "lang" with value "de" and "action" in the POST body.

All text in the ajax post reply will be in "de" instead of "fr" and I do not understand a word of that language.

This happens bc you have a bug in WPML_Locale->locale()

if ( $is_ajax && isset( $_REQUEST['action'], $_REQUEST['lang'] ) ) {
$locale_lang_code = preg_replace( '/[^-a-zA-Z0-9_]/', '', $_REQUEST['lang'] );

Practical use case (where this happens to us all the time):
when we modify a WooCommerce order, we have a button that will send an email and it also uses "lang" which contains the customers (!) language though.

Solution:
instead of using $_REQUEST use $_GET

Symptoms:
All text in the ajax post reply is in 'de' instead of 'fr'

Questions:
Fix your code