Description:
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The method DOMElement::setIdAttribute(attr, true) works incorrectly. When called twice, it removes identity from the attribute. This pull request - https://github.com/php/php-src/pull/7482 - contains the bug fix

Test script:
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$dom = new DOMDocument('1.0', 'utf-8');

$element = $dom->createElement('test', 'root');

$dom->appendChild($element);

$element->setAttribute("id", 123);
$element->setIdAttribute("id", true);

$node = $element->getAttributeNode("id");
echo $node->isId(), "\n";

$element->setIdAttribute("id", true);
echo $node->isId(), "\n";

Expected result:
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The second call must not remove ID from the attribute

Actual result:
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ID is removed from the attribute