Prefix: typo os.makedirs()
Variables: segregate proxy variables initialization

Variables as it is is a nightmare to unit test:
- environment variables are by definition global variables
- the module does lots of things when imported, based on environment
variables

Dropping the call to initialization() right into Variables to put it
somewhere on the caller so that the initialization time can be decided
would be an improvement.
TestPrefix: work around late Variables import issues

- Variables needs to be imported late so the environment variables can
be set first
- Prefix, like just about everything else, depends on Variables, so must
also be imported late
- ... not profit