Using the following code in 4.3.0-4.3.1 works,

# Start reading the XML response.
$xml = domxml_open_mem($xml_response);
$root = $xml->document_element();

However, the *exact* same code, compiled with the exact same flags in 4.3.2 results in:

Fatal error: Call to a member function on a non-object in /data/websites/client on line 74, line 74 being:

"$root = $xml->document_element();"

Roll back to 4.3.1, and it works fine.