obsolete code/docs in setPassExceptions

[joachim-n]

I'm not sure if the code needs updating, but the docs are definitely out of date:

     * The default behavior in the current (2.x) branch is to catch
     * the exception and replace it with a CommandError object that
     * may be processed by the normal output processing passthrough.
     *
     * In the 3.x branch, exceptions will never be caught; they will
     * be passed through, as if setPassExceptions(true) were called.
     * This is the recommended behavior.
     */
    public function setPassExceptions($passExceptions)