SOAP servlet generating invalid XML, breaks Python clients

The attached Python SOAP client essentially does:

token = soap.login(jirauser, passwd)
soap.getAllPermissions(token)

This breaks with a cryptic XML parse error:

unknown>:1:497: duplicate attribute

Further investigation reveals that JIRA is generating invalid XML in response to the SOAP query (see attached response.xml). The problem is the duplicated xsi:type attribute, which is duplicated (not allowed in XML):

<getAllPermissionsReturn soapenc:arrayType="ns2:RemotePermission[20]" xsi:type="soapenc:Array" xsi:type="soapenc:Array" ...