Tax rule is not applied with empty tax when creating purchases from purchase requests
See http://www.tryton.org/~irclog/latest.log.html#t2017-05-23%2016:02
This instance will be upgraded to Heptapod 1.3.3 (GitLab 16.9.6) on 2023-04-25 at 18:00 UTC+2
See http://www.tryton.org/~irclog/latest.log.html#t2017-05-23%2016:02