Description:
------------
Hello,
var_export generates useless empty string in some specials cases (tested on 5.6.2)

Test script:
---------------
$data = "\0\0\0\0\0\0\0";
var_export($data);

echo "\n\n";

$data = "ok\0\0\0ab";
var_export($data);

Expected result:
----------------
"\0\0\0\0\0\0\0"

'ok' . "\0\0\0" . 'ab'

Actual result:
--------------
'' . "\0" . '' . "\0" . '' . "\0" . '' . "\0" . '' . "\0" . '' . "\0" . '' . "\0" . ''

'ok' . "\0" . '' . "\0" . '' . "\0" . 'ab'