python(test): don't write bytecode

Tests are usually lauched from source directory, so additional unnecessary
files should be eliminated.

Alternative ways (command line):
- python -B ...
- PYTHONDONTWRITEBYTECODE=1 python ...

modules/python/test/test.py

@@ -2,6 +2,9 @@
 
 from __future__ import print_function
 
+import sys
+sys.dont_write_bytecode = True  # Don't generate .pyc files / __pycache__ directories
+
 import os
 import unittest