WSDL, unknown error on error service error

[eriksimonic]

When using HHVM the webservice response (in case of an error) the error is not given. Example:

PHP 5.6

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
   <SOAP-ENV:Body>
      <SOAP-ENV:Fault>
         <faultcode>2</faultcode>
         <faultstring>Access denied.</faultstring>
      </SOAP-ENV:Fault>
   </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

HipHop VM 3.4.2 (rel)
Compiler: tags/HHVM-3.4.2-0-g40d85d7386b3342ab848fc45c6892433c89ef5b2
Repo schema: 13cba877c4300d1d0481b3f40eb128a5115d4e08
Extension API: 20140829

<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/">
   <SOAP-ENV:Body>
      <SOAP-ENV:Fault>
         <faultcode>Receiver</faultcode>
         <faultstring>Unknown error</faultstring>
      </SOAP-ENV:Fault>
   </SOAP-ENV:Body>
</SOAP-ENV:Envelope>