Handling of empty specarg delimiter appear broken.

com.sun.java.util.jar.pack.Driver - lines 696-702:

                            String old = properties.get(opt);
                            if (old != null) {
                                // Append new val to old with embedded delim.
                                String delim = specarg;
                                if (delim.length() == 0) delim = " ";
                                strval = old + specarg + strval;
                            }