XML-RPC on fault return puts <em> tags into <string> resulting in loss of information

xmlrpcs.inc uses t() with placeholders when reporting error. The placeholde will be surrounded with <em> tags, and when the message parsing is done in xmlrpc.inc in xmlrpc_message_parse() parts of the message will be cropped.

Example: when requesting an invalid method the result is the following XML:

<methodResponse>
  <fault>
  <value>
    <struct>
    <member>
      <name>faultCode</name>
      <value><int>-32601</int></value>
    </member>
    <member>
      <name>faultString</name>
      <value><string>Server error. Requested method <em>node.loader</em> not specified.</string></value>
    </member>
    </struct>
  </value>
  </fault>
</methodResponse>

From which the parsed error will be:

[params] => Array
        (
            [0] => Array
                (
                    [faultCode] => -32601
                    [faultString] =>  not specified.
                )

        )

You can see that the fault string is only part of the original message, moreover it contains a leading white space, which suggests that there was a mistake when the original XML tags were removed. I suggest we remove the extra formatting tags from the faultString, so the parsed message can be retreived.

This bug is also there in Drupal 6, where the same faulty behaviour is expected, but I did not test it.

If you want to test the bug there is an xmlrpc tester module in my sandbox. Patch replaces the placeholders with the actual variables.