composer module | config command always returns changed

OS X 10.10.5
Python 2.7.11
Ansible 2.0.2.0
remote: Ubuntu 14.04.4 LTS
remote: Python 2.7.6
remote: PHP 5.5.9
remote: Composer version 1.2-dev

I notice in a play with the composer module that every invocation of
command=config to configure a certain key returns 'changed' status. Is
this the expected outcome?

Repeatedly executing this module returns 'changed' status each time:

$ ansible example.net -m composer -a 'command=config
arguments="vendor-dir Vendor" working_dir=/var/www/myapp' -bv
example.net | SUCCESS => {
    "changed": true,
    "msg": "Running composer as root/super user is highly discouraged
as packages, plugins and scripts cannot always be trusted"
}

$ ansible example.net -m composer -a 'command=config
arguments="vendor-dir Vendor" working_dir=/var/www/myapp' -bv
example.net | SUCCESS => {
    "changed": true,
    "msg": "Running composer as root/super user is highly discouraged
as packages, plugins and scripts cannot always be trusted"
}

The following tasks are used in this play, and each complete fine with
only the 'command=config' returning changed each time:

- name: composer | select cake-resque
  composer: command=require arguments='kamisama/cake-resque:4.1.2'
working_dir={{ app_path }}

- name: composer | configure vendor-dir
  composer: command=config arguments='vendor-dir Vendor'
working_dir={{ app_path }}

- name: composer | install something
  composer: command=install working_dir={{ app_path }}

I can verify that the composer.json file in the working directory has
the following contents at the end of every run:

{
    "require": {
        "kamisama/cake-resque": "4.1.2"
    },
    "config": {
        "vendor-dir": "Vendor"
    }
}

Is there anything that can prevent 'changed' status on any run of the
task after the first?

If it is intended that the module does not do this by itself, there is
always 'changed_when:'...
https://docs.ansible.com/ansible/playbooks_error_handling.html#overriding-the-changed-result

Johannes