Paste problem: overriding config.py settings in blog.ini doesn't work?

I'm trying to get my blog setup so that I can preview locally with
paste and then publish to a server with either CGI or static
rendering. Most of the config.py settings are the same when previewing
and when published but a few crucial ones (base_url) are different.
The docs show how you can use blog.ini to override config.py settings,
but this doesn't seem to work. Setting the config.py directory in
blog.ini doesn't work either, when you run paste it always reads the
config.py file in the current working directory.

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