nub list of sdist files to work around older cabal issue #2432
nub list of sdist files to work around older cabal issue #2432

mrkkrp/stack,Fuuzetsu/stack,anton-dessiatov/stack,MichielDerhaeg/stack,anton-dessiatov/stack,martin-kolinek/stack,juhp/stack,Fuuzetsu/stack,mrkkrp/stack,juhp/stack,MichielDerhaeg/stack,martin-kolinek/stack