Add VIRTUAL_ENV key to enviroment passed to patch_tox_env
Add VIRTUAL_ENV key to enviroment passed to patch_tox_env

Bug 1161413

Change-Id: I873d90c148c2adf15319faeb6290743eda2d52aa

moshele/networking-mlnx,moshele/networking-mlnx-master,stackforge/networking-mlnx,openstack/networking-mlnx,openstack/networking-mlnx,stackforge/networking-mlnx