If you try to set rwX permissions, ACL fails to set them at all.
Expected:
$ sudo setfacl -m 'group::rwX' www
...
drwxrwxr-x 2 root root 4096 Nov 10 17:09 www
With Ansible:
acl: name=/var/www permissions=rwX etype=group state=present
...
drwxrw-r-x 2 root root 4096 Nov 10 17:30 www
x for group is erased. =/