patch applied (testsuite): add test for #2122

[Simon Marlow]

Tue Feb 26 06:06:06 PST 2008  Simon Marlow <simonmar at microsoft.com>
  * add test for #2122

    A ./tests/ghc-regress/lib/IO/2122.hs
    M ./tests/ghc-regress/lib/IO/all.T +2