Fix venv for ./run_tests.sh -p

Currently just running pep8 with ./run_test.sh -p is not
using the venv because the wrapper definition was occurring
after tools/hacking.py was run. This moves the pep8 check to
after the venv setup to fix this issue.

Change-Id: Ie9fd2a427d8e8875d0cb0db885ea442b2d29ae73
Merge "Fix venv for ./run_tests.sh -p"