rostopic: list --host raises ValueError

[kakkoko]

Steps to reproduce:

1. Execute roscore on a terminal
2. Execute rostopic list --host on another terminal

Expected:

Host [vboxres]:
  /rosout
  /rosout_agg

Actual:

Host [vboxros]:
Traceback (most recent call last):
  File "/opt/ros/melodic/bin/rostopic", line 35, in <module>
    rostopic.rostopicmain()
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rostopic/__init__.py", line 2119, in rostopicmain
    _rostopic_cmd_list(argv)
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rostopic/__init__.py", line 2059, in _rostopic_cmd_list
    exitval = _rostopic_list(topic, verbose=options.verbose, subscribers_only=options.subscribers, publishers_only=options.publishers, group_by_host=options.hostname) or 0
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rostopic/__init__.py", line 1242, in _rostopic_list
    verbose, indent='  ')
  File "/opt/ros/melodic/lib/python2.7/dist-packages/rostopic/__init__.py", line 1150, in _sub_rostopic_list
    topics = list(set([t for t, _, _ in pubs] + [t for t, _, _ in subs]))                
ValueError: need more than 2 values to unpack

Note rostopic list worked as expected:

$ rostopic list
/rosout
/rosout_agg

Environment:

• Ubuntu 18.04.2 LTS
• ros-melodic-desktop-full/bionic,now 1.4.1-0bionic.20190618.145748 amd64
  • installed according to http://wiki.ros.org/melodic/Installation/Ubuntu

[artivis]

I can confirm the issue.
Ubuntu 18.04
rostopic 1.14.3

[danielwangksu]

the same, confirm the issue
Ubuntu 18.04
rostopic 1.14.3