Redirect stdout/stderr through the logging system.
This change also causes the uncaptured output of subprocesses to
be routed to the logging system for recording in the session
transcript.
Coverage: code coverage testing for Python
Coverage.py is a Python module that measures code coverage during test execution.
It uses the code analysis tools and tracing hooks provided in the Python standard
library to determine which lines are executable, and which have been executed.
For more information, see http://nedbatchelder.com/code/modules/coverage.html