Deploy validations fail for images

Issue

• overcloud deploy validation fails
• Validation: Verify existence of deployment images. fails with :
  output:

Task 'Check for required images' failed:
Host: localhost
Message: The conditional check '"" not in ""' failed. The error was: Invalid conditional detected: EOL while scanning string literal (<unknown>, line 1)

The error appears to have been in '/usr/share/openstack-tripleo-validations/validations/deployment-images.yaml': line 16, column 5, but may
be elsewhere in the file depending on the exact syntax problem.

The offending line appears to be:


  - name: Check for required images
    ^ here


Failure! The validation failed for all hosts:
* localhost