New issue 11 by tallpsm...@gmail.com: ThreadContext.clear() doesn't tidy up
MDC values properly.
http://code.google.com/p/parfait/issues/detail?id=11
ThreadContext.clear()
doesn't actually do the inner MDC.clear()
that's because MDC doesn't HAVE a clear..
but it's not clearing...
we really need to iterate over the MDC keys and remove.
because otherwise the MDC becomes tainted.