set ignore_basepython_conflict = True in tox.ini
set ignore_basepython_conflict = True in tox.ini

os-vif sets the base python version globally in the
base testenv and relies on tox to pick up the
correct python version form the env name for standard
envs like py27.

This behavior only work reliably if
ignore_basepython_conflict = True is set.

Change-Id: I458cf6cf88d9ee672d6cce59e1d86ed888957042
Closes-Bug: #1832652

openstack/os-vif