reads and simplify code.

handle correctly references to "bogus variable" (e.g. "prefix=$/opt/python").

correctly references to "bogus variable" (e.g. "prefix=$/opt/python").

each call to their encode() method anymore, but continue to call the reset()
method if the final argument is True.

each call to their encode() method anymore, but continue to call the reset()
method if the final argument is True.

their encode() method anymore, but continue to call the reset() method if the
final argument is True.

Add also a security warning in the module random pointing to ssl.RAND_bytes().

Fix a reference leak.

log level. Avoid also calls to .addCleanup() in setUp().

module.