Paver test_system -s lms (edx-organizations)

I’m installing edx-organizations from https://github.com/edx/edx-organizations in my native installed openedx hawthorn release.
When i run paver test_system -s lms, Build failed: Unknown task: test_system error occurs. How can i fix it?

If you could show the full error report (traceback), it might be easier to help.