I have applied this patch and uploaded cabal-debian-4.15.2 to hackage. It is worth noting that it would be better if I modified the BinPkgName and SrcPkgName types in the debian package so they prohibited creation of values containing upper case. Also, there is a more sophisticated mechanism for mapping cabal names to debian names. It allows you to do things like map versions of QuickCheck < 2 to libghc-quickcheck2-dev, others to libghc-quickcheck-dev. Unfortunately, the library is not (yet) 100% consistent in its treatment of library names because of its long seven year history.
-david