Description:
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I was saving a SimpleXML object and kept getting errors that the file could not be written. Upon further examination, I discovered that the directory containg an url-encoded slash (%2F) and while the directory existed as an encoded string (e.g. 'dir1%2Fdir2/file.xml') asXML was explicitly unencoding it and attempting to write to a different directory (which does not exist, e.g. 'dir1/dir2.xml'). No amounts of double-encoding the filename succeeded in creating the file successfully (same error) so I had to resort to file_put_contents("{$dirname}/file.xml", $sXML->saveXML());

Test script:
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$sXML = new SimpleXMLElement('<result />');
$filename = 'dir1%2Fdir2/result.xml';
mkdir(dirname($filename));
file_put_contents($filename, $sXML->asXML()); // works as expected
$sXML->asXML($filename); // fails; no such file/directory

Expected result:
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Filename arguments given to asXML should be accepted without url-decoding

Actual result:
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filenames are being url-decoded, which is not what I want or expect