patch applied (packages/Cabal): Check invariant on every construction and elide on lookups

[Ian Lynagh]

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/packages/Cabal/_darcs/patches/20080514154104-adfee-7ac2a950ca94eece4965c87b652a14024d503184.gz