I accidentally tried to pass logging levels as strings
to Logger.log() instead of numbers. The result was that
%(levelname)s produced the number of the level
specified and %(levelno)s produced the name... I
assumed that passing strings was valid, because if you
passed an unregistered level name, the %(levelname)s
would just say 'Level XYZ' instead of 'XYZ'.

The culprit is this dict in logging/__init__.py:

_levelNames = {
    CRITICAL : 'CRITICAL',
    ERROR : 'ERROR',
    WARNING : 'WARNING',
    INFO : 'INFO',
    DEBUG : 'DEBUG',
    NOTSET : 'NOTSET',
    'CRITICAL' : CRITICAL,
    'ERROR' : ERROR,
    'WARN' : WARNING,
    'WARNING' : WARNING,
    'INFO' : INFO,
    'DEBUG' : DEBUG,
    'NOTSET' : NOTSET,
}

I think it would be a good idea to split this dict into
two, so that such confusion doesn't result. Also, it
should be explicitly stated (in the docs and maybe in
code too) if a name of the level as a string argument
to Logger.log() is valid or not.

Logged In: YES 
user_id=308438

Current CVS Logger.log() throws an exception ("level must be 
an integer") if you don't pass an integer level, and if 
raiseExceptions is set.

The _levelNames approach is by design. It avoids having two 
dictionaries and two function calls.

Documentation/docstring for Logger.log() updated to indicate 
that "lvl" should be an integer.