This issue is about backporting the 69d50e2 commit patched in the improvement issue, MDL-64588.

The issue is that when several comments have the same exact timestamp (in seconds, which is possible), the get_comments() web service may return these in an unreliable way (the ordering of results when an explicit sort has not been declared is unknown). One call might return a before b and the next may return b before a. We should include the id in the sorting to make sure this is predictable.

This issue should include that change, and adjustments to the unit tests in order to confirm that change.