testr should preserve existing OS_* environment variables values

[Roman Podoliaka]

Currently .testr.conf specifies that tests are run by executing of the following command:
OS_STDOUT_CAPTURE=1 OS_STDERR_CAPTURE=1 OS_TEST_TIMEOUT=60 ${PYTHON:-python} -m subunit.run discover -t ./ ./nova/tests $LISTOPT $IDOPTION

It should be possible to override the values of OS_* environment variables without making changes to .testr.conf, so one can specify those env vars for each tox/runtests.sh call or for the current shell session using export syntax.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/29902

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/29902
Committed: http://github.com/openstack/nova/commit/e4b85c10a66075a8bd1241e9945843be549aa813
Submitter: Jenkins
Branch: master

commit e4b85c10a66075a8bd1241e9945843be549aa813
Author: Roman Podolyaka <email address hidden>
Date: Tue May 21 13:45:40 2013 +0300

    Make testr preserve existing OS_* env vars values

    Values for OS_TEST_TIMEOUT, OS_STDOUT_CAPTURE and OS_STDERR_CAPTURE
    environment variables are fixed in .testr.conf now. It should be possible
    to override them for each tox/runtests.sh call or for the current shell
    session without making changes to .testr.conf.

    Fixes bug 1182416.

    Change-Id: I6c7839fa78b53ac8ea358ce0143a00931da96a9e