rosmaster allows multiple nodes with same xmlrpc uri but different path names

[NickZ]

If multiple nodes have the same uri, but have different path names, rosmaster will allow the collision.

To test:

1. I have created a branch on my fork of ros_comm to allow manually setting the XML-RPC server port in the roscpp client, here: https://github.com/NickZ/ros_comm/tree/test_xmlrpc_port
2. Put my branch into a catkin workspace, along with the ros_tutorials, build it and source it.
3. Run roscore
4. Run rosrun roscpp_tutorials talker __xmlrpc_server_port:=22222 __name:="test1"
5. In another terminal, find the PID of that node and kill -9 it, to prevent it from sending unpublish to the master
6. rosnode list and confirm that /test1 is still in the rosnode list
7. Run rosrun roscpp_tutorials talker __xmlrpc_server_port:=22222 __name:="test2"
8. rosnode list and confirm that both /test1 and /test2 are still listed.
9. rosnode info test1 and rosnode info test2 to confirm that both are listed as having the same XMLRPC uri and both are listed as connectable.

[fujitatomoya]

@NickZ

im just curious what if issue #4 instead of #7, it will fail to register cz same URI with same node?
and also curious to use cached parameter usecase since that will subscribe parameter with URI.

thanks,