patch applied (cabal): Add PackageIndex.dependencyCycles

[Duncan Coutts]

Sun May  4 06:16:26 PDT 2008  Duncan Coutts <duncan at haskell.org>
  * Add PackageIndex.dependencyCycles
  Finds any cycles (strongly connected components) in the dependencies
  of set of packages. This is useful for checking the correctness of
  installation plans.

    M ./Distribution/Simple/PackageIndex.hs +18

View patch online:
http://darcs.haskell.org/cabal/_darcs/patches/20080504131626-adfee-73906b092fb48bd20ff2ed6aea47bea26ec886a5.gz