trust: handle stray pylint warning
    
    We only get to this code path when running in the server context. At
    that point _bindings_installed will be defined. Pylint cannot track this
    and always fails with this check.
    
    Signed-off-by: Alexander Bokovoy <abokovoy@redhat.com>
    Reviewed-By: Thomas Woerner <twoerner@redhat.com>
    Reviewed-By: Rob Crittenden <rcritten@redhat.com>
    Reviewed-By: Rafael Guterres Jeffman <rjeffman@redhat.com>