Git commits in Moodle 3.5.0 by Carlos Alexandre S. da Fonseca

commit 38e7a9525f22919c654dbc36c56acbe839fe4469
Author: Carlos Alexandre S. da Fonseca <bozohhot@hotmail.com>
Date:   Tue, 21 Nov 2017 20:29:09 +0800
Tag:    v3.5.0-beta

MDL-24678 mod_chat: Fixed race condition on chat module