replacing lines in a file

[mpnordland]

Attached are a config file parser that i'm working on, and a example 
config file. Basically, what my problem is is in write_config, it should 
search through the file, and replace the lines with whatever the 
modified version is, it is also designed to ignore comments. To see my 
problem (which is hard to describe) please first look at the config 
file, and then run config-parse.py then look at the config file again.
One of two things should happen: nothing, or something weird should 
happen on the last line.
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