relative URL in imagecache_create_url()

I would like to decide on my own wether imagecache_create_url() returns an absolute or a relative URL, just as url() does.

I could imagine something like

function imagecache_create_url($presetname, $filepath, $bypass_browser_cache = FALSE)
to
function imagecache_create_url($presetname, $filepath, $bypass_browser_cache = FALSE, $absolute = TRUE)
...
$args = array('absolute' => $absolute, 'query' => empty($bypass_browser_cache) ? NULL : time());

thanks in advance!

(would provide patch iff necessary.)