Latest omniorb version problem

[kyawawa]

When I was setting up ubuntu 18.04, I was faced with the problem related to omniorb version.

1st, omniorb_4.2.2-0.8, which is installed on ubuntu 18.04, seems to be built using python3.
https://ubuntu.pkgs.org/18.04/ubuntu-universe-amd64/omniorb_4.2.2-0.8_amd64.deb.html
So I got the import error at idl2srv

2nd, after converting idl2srv.py from python2 to python3, I faced version inconsistency error between omniORBpy and its stubs (? I don't understand what is "stubs")
I installed rtctree, rtshell and rtsprofile using pip because ros-melodic-rtctree has not been released yet.

$ rtls
omniORB: (0) 2019-04-09 14:07:32.290876: ERROR! omniORBpy version 4.2 expects stubs version 4.2. Stubs in /usr/local/lib/python2.7/dist-packages/rtctree/rtc/BasicDataType_idl.pyc are version 3.0 (rev 0).
Traceback (most recent call last):
  File "/usr/local/bin/rtls", line 7, in <module>
    from rtshell.rtls import main
  File "/usr/local/lib/python2.7/dist-packages/rtshell/rtls.py", line 26, in <module>
    import rtctree.tree
  File "/usr/local/lib/python2.7/dist-packages/rtctree/tree.py", line 27, in <module>
    from rtctree import exceptions
  File "/usr/local/lib/python2.7/dist-packages/rtctree/exceptions.py", line 22, in <module>
    from rtctree.rtc import RTC
  File "/usr/local/lib/python2.7/dist-packages/rtctree/rtc/RTC/__init__.py", line 9, in <module>
    import rtctree.rtc.BasicDataType_idl
  File "/usr/local/lib/python2.7/dist-packages/rtctree/rtc/BasicDataType_idl.py", line 7, in <module>
    _omnipy.checkVersion(3,0, __file__)
ImportError: Stubs not compatible with omniORBpy version 4.2.

I haven't looked into rtctree and so on, but it's just a quick report.