Checking for a package that isn't either a direct or indirect dependency is plain wrong. package.provided is not supported - it's the users fault, if he insists to sidestep Portage. There is no valid case for your construct. With regards to QA, it wouldn't be wrong to have a better solution, but given that built_with_use() is itself only a workaroud for still not having use dependencies, it's a bit pointless.
Carsten
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