The order of the partitions is important, it needs to be preserved.
If using a simple dict, this is not happening. As a consequence,
checks like 'primary partition being first' are failing because the
dictionary sorts the partitions randomly.
Switched to OrderedDict solved the problem, as it preserves the
ordering it gets from the yaml blob.
Change-Id: Icfa9bd95ffd0203d7c3f6af95de3a6f848c2a954