patch applied (cabal-branches/cabal-1.4): Check invariant on every construction and elide on lookups

[Duncan Coutts]

Wed May 14 08:41:04 PDT 2008  Duncan Coutts <duncan at haskell.org>
  * Check invariant on every construction and elide on lookups

    M ./Distribution/Simple/PackageIndex.hs -10 +12

View patch online:
http://darcs.haskell.org/cabal-branches/cabal-1.4/_darcs/patches/20080514154104-adfee-7ac2a950ca94eece4965c87b652a14024d503184.gz