add test for working Data.List.
add test for working Data.List.

Ignore-this: 4d36c46a0200e334f51ca655a153df98
intercalate was only added since ghc 6.6.  Another option would be to
not use it.

darcs-hash:20081023141423-72aca-98796ab027cbbfac21c63b56af18e214304f8739

shicks/shsh,shicks/shsh