Logging progname with Rails differs from Ruby

There are some differences in how Ruby 1.9.3-p198 and Rails 3.2.3 handle logging a program name.

# Standard Ruby Logger: logger.error('program name'){'message'} logger.error('program name'){exception}

# Rails: Rails.logger.error('message', 'program name') Rails.logger.error(exception, 'program name')

If trying to switch between the two, using the standard logging format with the Rails logger, I find that Rails ignores the block and logs the 'program name' as the message instead.

Attempting to use the Rails format in IRB errors out with: ArgumentError: wrong number of arguments (2 for 1)

Is this intentional or is it a bug? I haven't seen anything logged on it anywhere, but may not be looking in the right place.