Our hacking module is ancient and makes Python 3.6's f-strings to fail
PEP8 check. This commit bumps hacking to newer version and fixes
violations found by it.

Change-Id: If8769f7657676d71bcf84c08108e728836071425

Apparently it is possible to override Neutron's MTU setting through DHCP
agent. This may lead to a situation when node (VM) network will have a
different MTU than pod network. In such case setting pod network's MTU
on a Pod's veth pair will fail due to MTU mismatch.

This commit makes sure we detect such situation soon and produce a log
message with a hint about the root cause.

Change-Id: Ib694950c77ac7c3fd480f579b627dc79bfceac85
Closes-Bug: 1863212

In this change, we enable xtrace on devstack plugin script for
kuryr-kubernetes. It helps with diagnose possible issues during devstack
deployment.

Change-Id: Ib141dc6b625470d31c1527322fa22ac6629c9f07