logging_unterpolation is a very simple module that will patch python's built-in logging module to accept PEP-3101 compliant string formatting (using the str.format method) as well as falling back to accept the original string interpolation operator (% or 'modulo')
Here's a basic example:
>>> import logging
>>> from logging_unterpolation import patch_logging
>>> logging.basicConfig(level=logging.DEBUG)
>>> logging.debug('test')
DEBUG:root:test
>>> logging.debug('%s', 'test') # example of built-in string interpolation in log messages
DEBUG:root:test
>>> patch_logging()
>>> logging.debug('{0}', 'test') # format syntax not supported unless patched
DEBUG:root:test