Functional tests debug support

Pass OS_* options into tox debug venv in order to
debug functional tests in local, and install ipdb
to make code-debug more convenient.

Change-Id: Ib926948f2b9a52921cf7487fe16ef716481e3ceb

Author: kiwik

tox.ini

@@ -73,7 +73,10 @@ commands =
     coverage report
 
 [testenv:debug]
-commands = oslo_debug_helper -t openstackclient/tests {posargs}
+passenv = OS_*
+commands =
+    pip install -q -U ipdb
+    oslo_debug_helper -t openstackclient/tests {posargs}
 
 [testenv:docs]
 commands = python setup.py build_sphinx