Steps to reproduce are...

1. Earn a badge.
2. Go into your profile and click the badge.
3. Click download.

Expected the badge to download.

Page reloads and nothing happens.

Note that downloading from /badges/mybadges.php does work, it's only /badges/badge.php that doesn't work.

The issue seems to be on (or around) line 38 of badge.php...
if ($bake && ($badge->recipient == $USER->id)) {

On my local installation I have changed it to...

if ($bake && ($badge->recipient->id == $USER->id)) {

...which appears to have fixed it.