title: Failed to set permissions on the temporary files Ansible needs to create
body: <p>I have in two Ansible roles a need to <code>become_user</code> for an unprivileged user (e.g. to set the git answers and to <code>dconf dump</code> the current settings); I have set already <code>allow_world_readable_tmpfiles=True</code> in the <code>ansible.cfg</code> file, but still have the error message</p>
  <pre><code>Failed to set permissions on the temporary files Ansible needs to create when becoming an unprivileged user (rc: 1, err: chown: changing ownership of '/var/tmp/ansible-tmp-1613484534.333031-12971-165984005608584/': Operation not permitted
       chown: changing ownership of '/var/tmp/ansible-tmp-1613484534.333031-12971-165984005608584/AnsiballZ_command.py': Operation not permitted
  </code></pre>
  <p>I do not use ACL or anything similar (and do not want to) and I do not see how to run as privileged user. My understanding of the documentation is that the problem should not exist since Ansble version 2.1.</p>
  <p>I run on a 64bit aarch64 (raspi 4) with 5.8.0.-1015 kernel. ansible is:
  Ansible 2.9.9
  config file = /home/frank/Data/ansibleHost/ansible.cfg
  configured module search path = ['/home/frank/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3/dist-packages/ansible
  executable location = /usr/bin/ansible
  python version = 3.8.6 (default, Sep 25 2020, 09:36:53) [GCC 10.2.0]</p>
  <p>The task which causes the error is:</p>
  <pre><code>- name: write a dconf dump file before loading
    shell: dconf dump / &gt; &quot;{{remoteDir}}current&quot;
    become: True
    become_user: &quot;{{ this_user.user_name }}&quot;
    environment:
      DBUS_SESSION_BUS_ADDRESS: unix:path=/run/user/{{ this_user.user_uid }}/bus 
  </code></pre>
  <p>which runs on a Debian bullseye freshly installed (python3).</p>