* The old behavior required setting environment variables to
disable capture of stdout and stderr to allow debugging via pdb.
The new behavior requires enabling capture of stdout/stderr
instead. This is already the case in nova.
* testr behavior is unmodified.
* Tip 'o the hat to Robert Collins (lifeless)
Change-Id: Ica021eeab07d5a540ce42436c9cc8000c3fd239a