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
diff --git a/tools/install_venv_common.py b/tools/install_venv_common.py
index 8f91251..fd9076f 100644
--- a/tools/install_venv_common.py
+++ b/tools/install_venv_common.py
@@ -21,20 +21,12 @@
 Synced in from openstack-common
 """
 
+import argparse
 import os
 import subprocess
 import sys
 
 
-possible_topdir = os.getcwd()
-if os.path.exists(os.path.join(possible_topdir, "tempest",
-                               "__init__.py")):
-    sys.path.insert(0, possible_topdir)
-
-
-from tempest.openstack.common import cfg
-
-
 class InstallVenv(object):
 
     def __init__(self, root, venv, pip_requires, test_requires, py_version,
@@ -139,17 +131,12 @@
 
     def parse_args(self, argv):
         """Parses command-line arguments."""
-        cli_opts = [
-            cfg.BoolOpt('no-site-packages',
-                        default=False,
-                        short='n',
-                        help="Do not inherit packages from global Python"
-                             "install"),
-        ]
-        CLI = cfg.ConfigOpts()
-        CLI.register_cli_opts(cli_opts)
-        CLI(argv[1:])
-        return CLI
+        parser = argparse.ArgumentParser()
+        parser.add_argument('-n', '--no-site-packages',
+                            action='store_true',
+                            help="Do not inherit packages from global Python "
+                                 "install")
+        return parser.parse_args(argv[1:])
 
 
 class Distro(InstallVenv):