tox debugging throws AttributeError

[gordon chung]

the previous solution to debugging ceilometer unittests throws an error now:

======================================================================
ERROR: openstack.common.test (unittest.loader.ModuleImportFailure)
----------------------------------------------------------------------
ImportError: Failed to import test module: openstack.common.test
Traceback (most recent call last):
  File "/usr/lib64/python2.7/unittest/loader.py", line 252, in _find_tests
    module = self._get_module_from_name(name)
  File "/usr/lib64/python2.7/unittest/loader.py", line 230, in _get_module_from_name
    __import__(name)
  File "/opt/stack/ceilometer/ceilometer/openstack/common/test.py", line 33, in <module>
    import fixtures
  File "/opt/stack/ceilometer/.tox/venv/lib/python2.7/site-packages/fixtures/__init__.py", line 68, in <module>
    from fixtures.fixture import (
  File "/opt/stack/ceilometer/.tox/venv/lib/python2.7/site-packages/fixtures/fixture.py", line 26, in <module>
    from testtools.compat import (
  File "/opt/stack/ceilometer/.tox/venv/lib/python2.7/site-packages/testtools/__init__.py", line 59, in <module>
    from testtools.matchers._impl import (
  File "/opt/stack/ceilometer/.tox/venv/lib/python2.7/site-packages/testtools/matchers/__init__.py", line 83, in <module>
    from ._doctest import (
  File "/opt/stack/ceilometer/.tox/venv/lib/python2.7/site-packages/testtools/matchers/_doctest.py", line 7, in <module>
    import doctest
  File "/usr/lib64/python2.7/doctest.py", line 99, in <module>
    import unittest, difflib, pdb, tempfile
  File "/usr/lib64/python2.7/pdb.py", line 59, in <module>
    class Pdb(bdb.Bdb, cmd.Cmd):
AttributeError: 'module' object has no attribute 'Cmd'

we should debugging solution to be inline with suggestion here: https://wiki.openstack.org/wiki/Testr#Debugging_.28pdb.29_Tests

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/110707

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/110707
Committed: https://git.openstack.org/cgit/openstack/ceilometer/commit/?id=2dc6348c90f3dcf92e1e31e90b23d5fd593da6b0
Submitter: Jenkins
Branch: master

commit 2dc6348c90f3dcf92e1e31e90b23d5fd593da6b0
Author: gordon chung <email address hidden>
Date: Wed Jul 30 12:02:17 2014 -0400

    Debug env for tox

    Running a test with pdb was difficult because tox captures
    output and causes pdb prompt to quit.

    Tips for how to run with debug are provided here:
     https://wiki.openstack.org/wiki/Testr#Debugging_.28pdb.29_Tests

    This change puts these commands into a debug env in tox.ini so
    you can do a command like:

    tox -e debug pycadf.tests.test_cadf_spec

    and when it hits your breakpoint you'll get the debug prompt.

    Change-Id: Ic53a888e4e305d51159d1d6a2f962786a532e089
    Co-Authored-By: Brant Knudson <email address hidden>
    Closes-Bug: #1350424