Write end result to stderr

We currently close stdout's fd, which leads to everything that gets
choose's output piped will not actually get it. Will need to
investigate. Wondering if this ever worked properly...

choose

@@ -270,4 +270,4 @@ if __name__ == "__main__":
     with StreamTo():
         choice = do_it(choice)
     if choice is not None:
-        sys.stdout.write(choice + '\n')
+        sys.stderr.write(choice + '\n')