Output CSV duplicate

On the release version, the last line of the export CSV introduce a major bug :
the output is duplicate 2 times

// Add BOM for better Excel reading.
$output .= chr(0xEF) . chr(0xBB) . chr(0xBF) . $output;

the point "." is wrong here, it must be :

// Add BOM for better Excel reading.
$output = chr(0xEF) . chr(0xBB) . chr(0xBF) . $output;

And actually on my version, i just comment all the line because with excel you see wrong character.