py-jedi needs py-parso to work. Looking at the changelog the parso function was split off in v0.11.0 of jedi. Trying to use jedi without parso installed causes an error.
A commit references this bug:
Date: Thu May 3 13:42:34 UTC 2018
New revision: 468928
Update to version 0.12.0
Add textproc/py-parso as a dependency
Reported by: email@example.com
Thanks for the report! I added textproc/py-parso as a dependency and also updated the port to v0.12.0