Updated openstack/openstack
Project: openstack-dev/pbr  a38dc208cf0ed0b06f9ab2e517fc267a6c181b3e

Allow _run_cmd to run commands in any directory.

This is needed to avoid running pip install within the directory of
the test package on Python2.6, where it helpfully (not really)
installs the test package, not pbr.

Change-Id: I956ad29f68a32cb4d33af448333f649043e0a655