change in IO error messages

[Dean Herington]

In the 20021021 release candidate, a newline is now appended to IO error

messages, including in particular the case of (ioError (userError "user
message")).  I dislike this change for several reasons:

* It treats IO errors differently from other exceptions.  That is, (show
e) for
an Exception e has a newline appended for IO errors but not other
exceptions.
* It introduces an unnecessary inconsistency with GHC.
* It breaks HUnit, which needs to manipulate error message strings.

 -- Dean