The hub plugin should not allow submitting tasks with duplicate architectures

[thozza]

None of the plugins (hub, builder) check if the architecture list provided in the task contains duplicate architectures. IOW, one can submit a task with three architectures specified and all of them being the same architecture (e.g. 3x x86_64).

The osbuild-composer will accept such request just fine and it will build 3x the same image and upload it to Koji in overwriting mode (osbuild/osbuild-composer@bd7f074).

The build itself will most probably blow up in the KojiFinalize job when the osbuild-composer worker calls CGImport while specifying multiple outputs to import. All of them would reference the same filename, but the checksum will most probably differ (due to different timestamps and some UUIDs in the image).

The hub plugin should ideally check if the provided architectures list contains duplicates and return an error to the caller.

[thozza]

JSON schema should be able to check for this case -> https://json-schema.org/understanding-json-schema/reference/array.html?highlight=unique#id13