locale with space causes the translations/catalogue.XXX file exists "PHP Parse error:  syntax error"

When client use a special locale, such as: "e s_US", it will create a cache file "app/cache/prod/translations/catalogue.e s_US.php".

The line 8 of the cache file is:
$catalogueE s = new MessageCatalogue('e s', array (

That will cause the "php parse error, syntax" and "internal server error (HTTP Status 500)".
