Error using with python3

[Rezenders]

Is this package compatible with python3? I saw that there are a few commits related to this topic.

I am trying to build ROS from source using python3, everything builds just fine.
But when I run capability_server I get the following error:

Traceback (most recent call last):
  File "/ros_catkin_ws/install_isolated/lib/capabilities/capability_server", line 8, in <module>
    from rospy.impl import tcpros_service
  File "/ros_catkin_ws/install_isolated/lib/python3/dist-packages/rospy/__init__.py", line 49, in <module>
    from .client import spin, myargv, init_node, \
  File "/ros_catkin_ws/install_isolated/lib/python3/dist-packages/rospy/client.py", line 52, in <module>
    import roslib
  File "/ros_catkin_ws/install_isolated/lib/python3/dist-packages/roslib/__init__.py", line 50, in <module>
    from roslib.launcher import load_manifest  # noqa: F401
  File "/ros_catkin_ws/install_isolated/lib/python3/dist-packages/roslib/launcher.py", line 42, in <module>
    import rospkg
ImportError: No module named rospkg
================================================================================REQUIRED process [capability_server-7] has died!
process has died [pid 27571, exit code 1, cmd /ros_catkin_ws/install_isolated/lib/capabilities/capability_server __name:=capability_server __log:=/root/.ros/log/211af6f2-a85e-11eb-a4ff-0242ac110002/capability_server-7.log].
log file: /root/.ros/log/211af6f2-a85e-11eb-a4ff-0242ac110002/capability_server-7*.log
Initiating shutdown!
================================================================================

It seems that this package is still trying to import rospkg from python2. I don't know if I build it wrongly or if it is related to the package itself. Sorry if this is my mistake.

I am building the workspace like this:
$ export ROS_PYTHON_VERSION=3 && python3 ./src/catkin/bin/catkin_make_isolated --install -CMAKE_BUILD_TYPE=Release -j1 --catkin-make-args all

BTW, I am using ubuntu 18.04 and ROS melodic.