Description:
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The Collator::getSortKey() method and the collator_get_sort_key() functions have one extra parameter by reflection compared to the documentation ( 
https://secure.php.net/manual/en/collator.getsortkey.php).

If we call the method with 2 parameters the following warning is emitted:
Warning: Collator::getSortKey() expects exactly 1 parameter, 2 given
(Same type of bug as https://bugs.php.net/bug.php?id=74468, different method)

Test script:
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<?php

$method = new ReflectionMethod('Collator', 'getSortKey');
var_dump($method->getNumberOfParameters());
var_dump($method->getNumberOfRequiredParameters());
$method = new ReflectionFunction('collator_get_sort_key');
var_dump($method->getNumberOfParameters());
var_dump($method->getNumberOfRequiredParameters());

// outputs 2, 2, 3, 3,


Expected result:
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The ReflectionMethod parameters should have 1 parameter, the ReflectionFunction should expect 2 parameters

Actual result:
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The ReflectionMethod parameters has parameters, the ReflectionFunction has 3 parameters