python3: Fix traceback while running tests.

In python3 you can't sort mixed data, that is,
for example you can't have a dict that contains
strings and intergers. Otherwise you will get the
dreaded:

TypeError: unorderable types: DictOpt() < _ConfigFileOpt()

Change-Id: If712e1d51c1e1329093acb16ed6a84e9f0baf8c1
Signed-off-by: Chuck Short <chuck.short@canonical.com>
Merge "python3: Fix traceback while running tests."