I guess read_config could look at the input file's layout and intuit whether you're separating section markers from config variables.
Maybe just adding a configurable parameter like 'noExtraNewlines' that would put newlines only in-between sections when adding entries ? That is, the current scheme of the user's file use of newlines would be preserved. Only new entries would be adopting the configurable option. Concern is, many users coudl eventually modify the same INI file, each one adding newlines when he/she sees it fit.
How about then an INI file formatter that would straigthen this out according to a defined (and configurable) scheme ? ;-)