Fixed incorrect call to logging.debug() that transparently adds a handler to the root logger

Calling `logging.debug()` directly causes a `logging.StreamHandler` to be added to the default root logger `logging.getLogger()`.

This has terrible consequences when one wants to keep control over the handlers of the root logger.

The proposed change fixes that issues while keeping the log output if needed.

rfc6266.py

@@ -23,6 +23,9 @@ import os.path
 import re
 import sys
 
+LOGGER = logging.getLogger('rfc6266')
+LOGGER.addHandler(logging.NullHandler)
+
 __all__ = (
     'ContentDisposition',
     'parse_headers',
@@ -170,7 +173,7 @@ def parse_headers(content_disposition, location=None, relaxed=False):
     """Build a ContentDisposition from header values.
     """
 
-    logging.debug(
+    LOGGER.debug(
         'Content-Disposition %r, Location %r', content_disposition, location)
 
     if content_disposition is None: