Custom Hooks Not Work 9.0.5

Same as here https://gitlab.com/gitlab-org/gitlab-ce/issues/34522

My folder for custom_hooks:

[root@leo custom_hooks]# ls -al
total 12
drwsrwsrwx 2 git git 4096 Sep 20 10:44 .
drwxrwx--- 8 git git 4096 Sep 20 10:41 ..
-rwsrwsrwx 1 git git  185 Sep 20 10:40 post-merge

[root@leo admin.git]# cd .. && ls hooks
post-receive  pre-receive  update

The script is very simple: pull in the testing folder

#!/bin/bash

cd $WWW/admin
git checkout develop
git pull

After a merge request accepted in GitLab, no updates (no pull) take place.