Comment 1 for bug 1510288

OK, but this is a new package in Trusty and docker.io in Trusty has never built against arm64, powerpc or ppc64el. So this isn't an SRU regression.

I guess we could fix this in the backport, although it's a bit awkward since we're using a script to generate the backports and I'd prefer to not have to special case this one. But does it gain anything if we're not aiming to enable extra architectures for Docker in Trusty anyway?