Saving agent template fails because of image collision

15:06:27.887 ERROR:workitem(27908): Houston? Houston!
Traceback (most recent call last):
  File "/home/vmbuilder/qt-ci/src/workitem.py", line 286, in _run
    await self.run()
  File "/home/vmbuilder/qt-ci/src/workitem.py", line 734, in run
    raise AgentException(reasons=("An instruction failed."))
  File "/home/vmbuilder/qt-ci/src/agentlauncher.py", line 169, in __aexit__
    await self._exit_action()
  File "/home/vmbuilder/qt-ci/src/opennebulahardwarepool.py", line 360, in save_agent_as_template
    await one.image.rename(image_id, template_name)
  File "/home/vmbuilder/qt-ci/src/opennebula/opennebula.py", line 131, in __call__
    result = await asyncio.wait_for(f, timeout=15 * 60, loop=loop)
  File "/usr/lib/python3.5/asyncio/tasks.py", line 392, in wait_for
    return fut.result()
  File "/usr/lib/python3.5/asyncio/futures.py", line 274, in result
    raise self._exception
  File "/usr/lib/python3.5/concurrent/futures/thread.py", line 55, in run
    result = self.fn(*self.args, **self.kwargs)
  File "/home/vmbuilder/qt-ci/src/opennebula/opennebula.py", line 119, in callSync
    raise ONEException(errorCode, data)
opennebula.opennebula.ONEException: (2048, '[one.image.rename] image cannot be renamed to qtci-windows-7-x86_64-4-519709 because it collides with image 1350')