Example line: https://github.com/pimutils/todoman/blob/master/contrib/completion/zsh/_todo#L46
containing: s/^[^#]\s*path\s*=\s*\(.*\)$/\1/p
requires the string to start with any character but # followed by any amount of spaces, followed by path and so on.

To currently make it work one has to make the configuration lines start with a whitespace for the regular expression to match, since [^#] requires any character but #.

There are more similar regular expressions below.