The IPMI power commands fail in py3.5 environment.
The details can be seen at http://logs.openstack.org/72/471072/5/experimental/gate-tempest-dsvm-ironic-ipa-partition-pxe_ipmitool-tinyipa-python3-ubuntu-xenial-nv/6b42b12/logs/screen-ir-cond.txt.gz?level=WARNING
Jun 07 06:56:29.472799 ubuntu-xenial-rax-ord-9179412 ironic-conductor[2669]: ERROR ironic.drivers.modules.ipmitool [None req-a489b980-6482-42fd-a77b-06071e7b162b None None] IPMI Error while attempting "ipmitool -I lanplus -H 166.78.116.6 -L ADMINISTRATOR -p 6230 -U admin -R 12 -N 5 -f /tmp/tmpeijj862w chassis bootdev pxe options=persistent" for node 8633468f-6baa-4bc4-9e94-ea7b1b92ad46. Error: Unexpected error while running command.
Jun 07 06:56:29.472947 ubuntu-xenial-rax-ord-9179412 ironic-conductor[2669]: Command: ipmitool -I lanplus -H 166.78.116.6 -L ADMINISTRATOR -p 6230 -U admin -R 12 -N 5 -f /tmp/tmpeijj862w chassis bootdev pxe options=persistent
Jun 07 06:56:29.473155 ubuntu-xenial-rax-ord-9179412 ironic-conductor[2669]: Exit code: 1
Jun 07 06:56:29.473318 ubuntu-xenial-rax-ord-9179412 ironic-conductor[2669]: Stdout: ''
Jun 07 06:56:29.473453 ubuntu-xenial-rax-ord-9179412 ironic-conductor[2669]: Stderr: 'Set Chassis Boot Parameter 5 failed: Unspecified error\n': oslo_concurrency.processutils.ProcessExecutionError: Unexpected error while running command.
Jun 07 06:56:29.473584 ubuntu-xenial-rax-ord-9179412 ironic-conductor[2669]: Command: ipmitool -I lanplus -H 166.78.116.6 -L ADMINISTRATOR -p 6230 -U admin -R 12 -N 5 -f /tmp/tmpeijj862w chassis bootdev pxe options=persistent
Jun 07 06:56:29.473727 ubuntu-xenial-rax-ord-9179412 ironic-conductor[2669]: Exit code: 1
Jun 07 06:56:29.473856 ubuntu-xenial-rax-ord-9179412 ironic-conductor[2669]: Stdout: ''
Jun 07 06:56:29.473983 ubuntu-xenial-rax-ord-9179412 ironic-conductor[2669]: Stderr: 'Set Chassis Boot Parameter 5 failed: Unspecified error\n'
I'm fairly sure this has been since fixed. Marking as such as we are running it with later python3 versions, and have since dropped python 3.5 support.