which will throw an Exception ���Cannot change an open stream to append mode���.
This is caused because of a flaw in the call chain.
*clojure.contrib.io/writer* for Strings calls again *writer* for whatever *clojure.contrib.io/output-stream*
returns. We call *append-writer* which then calls *writer* on the String which in turn then calls:
output-stream for ^String which calls
output-stream for ^URL which calls
output-stream for ^File which binds *append* to false and calls
output-stream for ^OutputStream which
returns a BufferedOutputStream instance which then jumps back to the
^File handler, which removes its binding for *append*!! and returns the BOS to the
^URL handler which returns the BOS to the