link to other topic does not work

All links are incorrect on page help/views/about.

The problem is in function advanced_help_view_topic.

example:

$output = preg_replace('/href="topic:([^"]+)"/', 'href="' . url('help/$1') . '"', $output);

link href="topic:views/field"
current result: href="help/$1"
expected result: href="help/views/field"

reason:
the url function changes the $ sign to %24 and preg_replace does not treat %241 as the reference to $1.

The function advanced_help_view_topic should be corrected..