Sort output for unit tests in test_describe_tags before compare

There's no guarantees on what order the output from describe_tags
comes back in, so it needs to be sorted.

Partially fixes bug #1192715

Change-Id: Ibb2619e8077ea8b8bd4796f9ffe89c2376d047f6
Merge "Sort output for unit tests in test_describe_tags before compare"