Distributions with spaces in name silently fail

Currently there is a [Stackage distro](http://hackage.haskell.org/distro/Stackage/packages) (created for me by @hesselink) which I populate each time I do a Stackage Nightly or LTS Haskell build. However, those package sets will quickly be diverging in the future, so I'm wondering if it would make sense to have two distributions: one for Nightly, one for LTS.

I'm bringing this up on the issue tracker as it's very much related to discussions I've had with @dcoutts about how Hackage may, in the future, be able to host such package sets. Theoretically each upload I do here is enough information for Hackage to start hosting such subsets, though there's no versioning history. I'm wondering if, instead of just making a tiny tweak to add an extra distribution name, there might be a larger change desired here instead.