add default path to PATH. log a warning if PATH is undefined , else add the default path to the end.
add default path to PATH. log a warning if PATH is undefined , else
add the default path to the end.

pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus,pegasus-isi/pegasus