Sync latest install_venv_common.py

Syncs:

c78b2ab Avoid using cfg in install_venv_common

So that people don't need oslo-config installed to run install_venv

Change-Id: Ie9b703255e8fdd1faa32b4e995efd858b3801801
Sync latest setup.py from oslo.

This commit syncs the lastest version of setup.py from oslo,
which includes:

8842a00 openstack.common.setup: fails to get version from git
8ce5947 Change the check for the existence of .git directory.
7417a60 returncode for Popen is valid only after communicate call

Change-Id: I491381b2f9cb178bb1d9aa9e790cc7fd11a67d2f
Merge "Sync latest install_venv_common.py"
Merge "Sync latest setup.py from oslo."