def image_for_distro(distro):
    """Return the container image name or path for a test distro name.

    The returned value is suitable for use with `docker pull`.

    >>> image_for_distro('centos5')
    'public.ecr.aws/n5z0e8q9/centos5-test'
    >>> image_for_distro('centos5-something_custom')
    'public.ecr.aws/n5z0e8q9/centos5-test'
    """
    return 'public.ecr.aws/n5z0e8q9/%s-test' % (distro.partition('-')[0],)