VID-1767 Add extra logging to updateThumbnailTask

This looks a little funky to have an unindented comment in the previous conditional block.  I get that its supposed to be for the second conditional, but maybe reformatting this would help?
```
if ( $status->isGood() ) {
    // Comment about good status
    if ( $file->getSha1() != self::DEFAULT_THUMB_SHA ) {
        log("good");
    }
} else {
    log("no good");
}
```