patch applied (cabal-install): Be more robust when dealing with external tar

[Pepe Iborra]

Sun May 20 13:21:37 PDT 2007  Pepe Iborra <mnislaih at gmail.com>
  * Be more robust when dealing with external tar

    M ./src/Network/Hackage/CabalInstall/TarUtils.hs -2 +3
    M ./src/Network/Hackage/CabalInstall/Update.hs -2 +2