Description of problem:
atomic pull image is failed and got error as subject, it should be caused by lost /etc/containers/policy.json file.

Version-Release number of selected component (if applicable):

[root@atomic-host-001 cloud-user]# atomic host status
State: idle
Deployments:
● rhel-atomic-host:rhel-atomic-host/7/x86_64/standard
       Version: 7.3 (2016-10-26 14:24:09)
        Commit: 90c9735becfff1c55c8586ae0f2c904bc0928f042cd4d016e9e0e2edd16e5e97
        OSName: rhel-atomic-host
  GPGSignature: (unsigned)
      Unlocked: development

[root@atomic-host-001 cloud-user]# rpm -q atomic skopeo
atomic-1.13.3-1.el7.x86_64
skopeo-0.1.17-0.4.git550a480.el7.x86_64

How reproducible:
always

Steps to Reproduce:
1. atomic host unlock
2. download latest atomic, skopeo RPM pacakges from brew system
3. rpm -Uvh atomic*.rpm skopeo*.rpm
4. atomic --debug pull registry.access.redhat.com/rhel7


Actual results:

[root@atomic-host-001 cloud-user]# atomic --debug pull registry.access.redhat.com/rhel7
Image registry.access.redhat.com/rhel7 is being pulled to docker ...
argument of type 'NoneType' is not iterable
Traceback (most recent call last):
  File "/bin/atomic", line 186, in <module>
    sys.exit(_func())
  File "/usr/lib/python2.7/site-packages/Atomic/pull.py", line 65, in pull_image
    handler()
  File "/usr/lib/python2.7/site-packages/Atomic/pull.py", line 49, in pull_docker_image
    trust.discover_sigstore(fq_name)
  File "/usr/lib/python2.7/site-packages/Atomic/trust.py", line 282, in discover_sigstore
    if not scope in registry_configs:
TypeError: argument of type 'NoneType' is not iterable

Expected results:


Additional info: