
All the platforms we care about now have python3 with venv (even centos7 now) packaged somehow. Add an ensure-venv element to make sure that "python3 -m venv" works. Any other elements that wish to install non-distribution-packaged Python utilities can use this to keep them separate from the main system installs. Port glean to use this, and drop its dependency on pip-and-virtualenv. Change-Id: Ic16f134fe34293bb68e7c632dd320f523366320d
ensure-venv
A simple element to make sure python3 -m venv will work.