Packages kept in testing due to d-i despite being removed in unstable

[Niels Thykier <niels@thykier.net>]

Hi,

I noticed that nslu2-utils was removed from unstable (#869430) in August
2017, but at the moment we have a constraint to keep it in testing for d-i.

Please let us know when we can drop this constraint and let britney
remove nslu2-utils from testing.

Thanks,
~Niels