Legacy print statements are syntax errors in Python 3 but print() function works as expected in both Python 2 and Python 3.
Old style exceptions are syntax errors in Python 3 but new style exceptions work as expected in both Python 2 and Python 3.
* chore: fix lint warnings
* chore: another try at python import errors
Looks like the problem is that dbus_mock.py is running as
a script but living in the `lib/` directory where it's part of a
module. Moving it up into the `script/` directory seems to
solve the issue.
