Phalcon\Crypt\decryptBase64() modifies its argument

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Test case:

<?php
$crypt   = new \Phalcon\Crypt();
$source  = 'Life is much too short to be intoxicated';
$key     = 'very secret key';

do {
        $dest = $crypt->encryptBase64($source, $key, true);
} while (false === strpos($dest, '-'));
$copy    = (string)$dest;
$crypt->decryptBase64($dest, $key, true);
echo $dest, PHP_EOL;
echo $copy, PHP_EOL;
?>

Expected result: $dest === $cat
Sample actual result:

86j0nXjOaH7wJgpTa3zcsHVNu9KnvV6fGQsL2h/qTh5EzOPYapYJ6FZa2Hbo1ptG4W0pUV+PjlE4FYbSxgmszOFcZSUarKuCO/cAkySybEak+K+L0v7kDmJ/9bKXfF0b
86j0nXjOaH7wJgpTa3zcsHVNu9KnvV6fGQsL2h_qTh5EzOPYapYJ6FZa2Hbo1ptG4W0pUV-PjlE4FYbSxgmszOFcZSUarKuCO_cAkySybEak-K-L0v7kDmJ_9bKXfF0b

- is replaced with +; but because $source is not a reference it must not be modified.