patch applied (cabal-install): Packages are only invalid if they have more than zero problems.

[Duncan Coutts]

Mon May  5 02:05:13 PDT 2008  Duncan Coutts <duncan at haskell.org>
  * Packages are only invalid if they have more than zero problems.

    M ./Hackage/InstallPlan.hs -2 +4

View patch online:
http://darcs.haskell.org/cabal-install/_darcs/patches/20080505090513-adfee-28c25b76fed9c0b3f4db73e2066d5056ce1ec2db.gz