Waiverdb has a notion of "obsolete" waivers. That is, if I submit a waiver record for a particular test case and subject, tomorrow I can submit a new waiver for the same test case and subject with a different waived value (for example change True to False) or a different comment (with a better explanation, etc). This is part of the original Waiverdb design, it lets us achieve immutability of the waivers for auditing purposes, while still allowing users to change their mind about things. Consuming tools like Greenwave are supposed to only look at non-obsolete waivers when making decisions.

However, at present, Waiverdb is using the wrong criteria to group waivers. The API is only returning the most recent waiver for a particular test case--subject combination.

That means, if @ralph submits a waiver for some test case and subject, and then I also submit a waiver for the same test case and subject, WaiverDB will only return my waiver. Ralph's will be obsoleted.

Similarly if there are waivers for the same test case and subject but for different product versions (for example 'fedora-27' vs. 'fedora-26').

WaiverDB should consider these waivers distinct from each other, not obsoleting each other. If the product version or username are different then both the waivers should be returned by the API.