Changing media fails

With xen-4.1.6.1 changing the CD-ROM media fails as xend mixes passing arguments as "int" and "str".

Traceback (most recent call last):
  File "/usr/lib/python2.5/site-packages/xen/web/SrvBase.py", line 85, in perform
    return op_method(op, req)
  File "/usr/lib/python2.5/site-packages/xen/xend/server/SrvDomain.py", line 201, in op_device_configure
    req)
  File "/usr/lib/python2.5/site-packages/xen/xend/server/SrvDomain.py", line 171, in call
    return FormFn(fn, args)(req.args)
  File "/usr/lib/python2.5/site-packages/xen/xend/Args.py", line 166, in __call__
    return self.call_with_form_args(self.fn, fargs, xargs=xargs)
  File "/usr/lib/python2.5/site-packages/xen/xend/Args.py", line 138, in call_with_form_args
    return fn(*params, **keys)
  File "/usr/lib/python2.5/site-packages/xen/xend/XendDomainInfo.py", line 1099, in device_configure
    dev_uuid = dev_control.reconfigureDevice(devid, dev_config)
  File "/usr/lib/python2.5/site-packages/xen/xend/server/blkif.py", line 128, in reconfigureDevice
    (dev, mode) = self.readBackend(devid, 'dev', 'mode')
  File "/usr/lib/python2.5/site-packages/xen/xend/server/DevController.py", line 439, in readBackend
    raise VmError("Device %s not connected" % devid)
VmError: Device 832 not connected

Patch was sent upstream, but not accepted as xen-4.1 is EOL by now: <http://lists.xen.org/archives/html/xen-devel/2013-05/msg02496.html>

For reference our bug-entry: <https://forge.univention.org/bugzilla/show_bug.cgi?id=23394>