Description of problem:
When SELinux is set to disabled (not permissive or enforcing) the atomic command throws a stack trace attempting to install a new system container.

Version-Release number of selected component (if applicable):
1.22.1

How reproducible:
When SELinux is disabled, every time.

Steps to Reproduce:
1. Fully disable SELinux
2. Restart the machine
3. atomic install --system --system-package=no registry.access.redhat.com/rhel7/etcd

Actual results:
Traceback (most recent call last):
  File "/usr/bin/atomic", line 185, in <module>
    sys.exit(_func())
  File "/usr/lib/python2.7/site-packages/Atomic/install.py", line 134, in install
    return be.install(self.image, self.name)
  File "/usr/lib/python2.7/site-packages/Atomic/backends/_ostree.py", line 128, in install
    return self.syscontainers.install(image, name)
  File "/usr/lib/python2.7/site-packages/Atomic/syscontainers.py", line 578, in install
    return_value = self._install(image, name)
  File "/usr/lib/python2.7/site-packages/Atomic/syscontainers.py", line 706, in _install
    self._checkout_wrapper(repo, name, image, 0, SystemContainers.CHECKOUT_MODE_INSTALL, values=values, remote=self.args.remote, system_package=self.args.system_package)
  File "/usr/lib/python2.7/site-packages/Atomic/syscontainers.py", line 817, in _checkout_wrapper
    return self._checkout(repo, options)
  File "/usr/lib/python2.7/site-packages/Atomic/syscontainers.py", line 848, in _checkout
    raise e
OSError: [Errno 22] Invalid argument


Expected results:
Successful installation

Additional info:
This was reported by a user on RHEL 7.4 on freenode.

A fix already exists: https://github.com/projectatomic/atomic/commit/119f1236bb08b079241b6ad64230e58fec217f26