Log Message:
Update to 4000.2.10

changes:
4000.2.10
 - Merge pull request #48 from nominolo/master
   Fix severe performance issue affecting "cabal update"
   * Turn O(n^2) reverse into O(n)
     This patch improves `cabal update` performance by 10x(!) on my system.
     Due to this issue, `cabal update` was using an extreme amount of CPU,
     while it should be I/O-bound.  The reverse was taking 79s, now it
     takes 0.01s.
 ( #48 => https://github.com/haskell/HTTP/pull/48 )