patch applied (cabal-install): Extend the invariant on the Constraints ADT

[Duncan Coutts]

Fri Dec 19 11:23:09 PST 2008  Duncan Coutts <duncan at haskell.org>
  * Extend the invariant on the Constraints ADT
  It now carries around the original version of the database
  purely so that it can do a much more extensive consistency
  check. Packages are never gained or lost, just transfered
  between pots in various slightly tricky ways.

    M ./Distribution/Client/Dependency/TopDown/Constraints.hs -19 +61

View patch online:
http://darcs.haskell.org/cabal-install/_darcs/patches/20081219192309-adfee-a0073314277a04288bebbedc9e393b6496ad94a2.gz