When writing tests, it is useful to be able to look at the database
being modified. Since we use OVS virtual environments and delete
them when the test ends, this is difficult to do.
This patch adds the ability to pass KEEP_ENV=1 when running tox to
keep the virtual environment around and adds tools/debug_venv to
launch an OVS sandbox using the OVS virtual environment.
Change-Id: Idbec2d544d913ffa8888a050b8a53d016c0315f2
Terry Wilson