1.0.27.9: fix print-object cache handling

1.0.27.9: fix print-object cache handling
	1.0.25.50 exposed a bug in the print-object discriminating
	function: we need to have the methods for critical printing at
	all times, but the implementation allowed other methods into
	that initial cache, which was wrong if those methods
	were subsequently invalidated.  The fix is to keep the initial
	cache pristine and to use only copies in the print-object
	generic function itself.