Google fonts URL encodes Open Sans twice

The current Google font stylesheet specifies both Open Sans and Roboto, but Open Sans is not included because urlencode() changes the plus sign to %2B.
https://fonts.googleapis.com/css?family=Open%2BSans%3A400%2C600%2C700%2C800%7CRoboto%3A300%2C400%2C500%2C700%2C900&subset=latin%2Clatin-ext

You could replace the plus sign with a space. Then urlencode() would convert that space to a plus sign for the correct URL.

$font_families[] = 'Open Sans:400,600,700,800';

https://themes.trac.www.ads-software.com/browser/techup/1.24/inc/template-functions.php#L42