Description:
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When trying to rename a file to a file name that already exists script fails

Reproduce code:
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$file = fopen($filename, 'w');
fwrite($file, "Data");
fclose($file);
$rv = rename($filename,$Exitingfile);

Expected result:
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I would expect the existing file to be overidden and now have the new data in it.

Actual result:
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The existing file remains aswell as the new file.