Allow multiple results per product when more than 1 sha

[lukebjerring]

Description

Changes the behaviour of querying for multiple shas, to not implicitly set a max-count of one result for each product. (For other queries, such as no params, the default is one result per product).

If a user wants exactly one result per product (across 2 shas) they can add the param explicitly.

[wpt-pr-bot]

Staging instance deployed by Travis CI!
Running at https://shas-dot-wptdashboard-staging.appspot.com

[lukebjerring]

Example from #912 :
https://shas-dot-wptdashboard-staging.appspot.com/results/?label=master&shas=5dd605c,c522b88&product=chrome&diff

[Hexcles]

Change the behaviour of querying for multiple shas without to not implicitly set a max-count of one result for each product.

I'm having trouble parsing this sentence. Besides, could you explain the motive a bit more?

[lukebjerring]

Sorry, I typed many word do the explain. Revised to be interpretable as English.

We added support for multiple SHA params as part of the ?pr=123 support, but it behaves strangely. this pr makes it behaves more as you might expect (if you ask for more than one Sha, you get all results across those shas)

[Hexcles]

That makes sense. LGTM!

[Hexcles]

If there's existing tests related to the default value of limit, I'd like you to make them cover the new condition. Otherwise, it's perhaps not that important.

[lukebjerring]

Currently untested - tests would need a refactor. Separate PR.