+request-builds page for a snap configured to infer the series from snapcraft.yaml doesn't allow to select architectures

[Olivier Tilloy]

When I request builds for a snap that's configured to target bionic, the +request-builds page displays a list of checkboxes to allow me to select which architectures I want to request the build for.

For a snap that's configured to infer the series from snapcraft.yaml however, the +request-builds page doesn't display these checkboxes, so requesting a build will trigger builds for all configured architectures.

Cristian and Colin pointed me to the following comment in Launchpad's code: "Architecture selection is still useful even when the series is inferred from snapcraft.yaml, but it's more difficult to work out what choices to offer. For now we just make it all-or-nothing in that case."

That's an acceptable limitation, but the difference in UI is slightly confusing, maybe this should be explained on the +request-builds page?

[Dimitri John Ledkov (xnox)]

But it is trivial to offer those that are configured/enabled for the snap.

So just offer the choice of `snap.processors_collection_link`.

I.e. i configure the snap for arm64 s390x. and then request-builds page should offer me tickboxes to build selectively for either arm64 or s390x or both.

Even when series is inferred from snapcraft.yaml.