Changes to base

Changes to base:
commit c68f56488be342ef34a6808f32232a4dd4bd713b
Author: Joachim Breitner <mail@joachim-breitner.de>
Date:   Wed Dec 4 10:30:45 2013 +0000

    Avoid unsafeCoerce# in TopHandler

    instead use `... >> fail "..."` to turn IO () into IO a.