PHP Fatal error: __clone method called on non-object

The below error is caught and logged into my Nginx error log:

*962 FastCGI sent in stderr: "PHP message: PHP Fatal error: __clone method called on non-object in /var/www/xxx/sites/all/modules/token/token.tokens.inc on line 1403" while reading response header from upstream, client: my-own-ip, server: xxx.com, request: "GET /world HTTP/1.1", upstream: "fastcgi://unix:/var/run/php5-fpm.sock:", host: "xxx.com", referrer: "http://xxx.com/user"

I get the same on-screen error when I put the same site on Apache:

Fatal error: __clone method called on non-object in /var/www/xxx/sites/all/modules/token/token.tokens.inc on line 1403

I have tested token version 7.x-1.5, 1.5-dev and 1.4. All of them give the same fatal error.

Once I disabled the module, the fatal error is gone.

Line 1403 of token.tokens.inc is:

$entity = clone $data['entity'];

So I'd tried to print_r($data['entity'] just before this statement to check what is it. The following is the output:

stdClass Object ( [fid] => 392 [uid] => 83 [filename] => picture-83-1357192371.jpg [uri] => public://pictures/picture-83-1357192371.jpg [filemime] => image/jpeg [filesize] => 70559 [status] => 1 [timestamp] => 1357192371 [type] => image [field_file_image_alt_text] => Array ( ) [field_file_image_title_text] => Array ( ) [rdf_mapping] => Array ( ) [metadata] => Array ( ) ) stdClass Object ( [fid] => 392 [uid] => 83 [filename] => picture-83-1357192371.jpg [uri] => public://pictures/picture-83-1357192371.jpg [filemime] => image/jpeg [filesize] => 70559 [status] => 1 [timestamp] => 1357192371 [type] => image [field_file_image_alt_text] => Array ( ) [field_file_image_title_text] => Array ( ) [rdf_mapping] => Array ( ) [metadata] => Array ( ) [alt] => ) 631

I tried to tidy up this output as below:

stdClass Object ( 
   [fid] => 392 
   [uid] => 83 
   [filename] => picture-83-1357192371.jpg 
   [uri] => public://pictures/picture-83-1357192371.jpg
   [filemime] => image/jpeg
   [filesize] => 70559
   [status] => 1
   [timestamp] => 1357192371
   [type] => image
   [field_file_image_alt_text] => Array ( ) [field_file_image_title_text] 
                                           => Array ( ) [rdf_mapping] 
                                           => Array ( ) [metadata]
                                           => Array ( ) 
)
 
stdClass Object (
 [fid] => 392
 [uid] => 83
 [filename] => picture-83-1357192371.jpg
 [uri] => public://pictures/picture-83-1357192371.jpg
 [filemime] => image/jpeg
 [filesize] => 70559
 [status] => 1
 [timestamp] => 1357192371
 [type] => image
 [field_file_image_alt_text] => Array ( ) [field_file_image_title_text]
                                         => Array ( ) [rdf_mapping] 
                                         => Array ( ) [metadata] 
                                         => Array ( ) [alt] 
                                         => 
) 631