fix tracker.py when got 127.0.0.1 for the root node
fix tracker.py when got 127.0.0.1 for the root node

dmlc/ps-lite,dmlc/ps-lite,shilad/ps-lite,xcgoner/ps-lite-new,xcgoner/ps-lite-new,xcgoner/ps-lite-new,dmlc/ps-lite,dmlc/ps-lite,shilad/ps-lite,shilad/ps-lite,xcgoner/ps-lite-new