2018-09-13 15:21:53,637 ERROR zuul.Scheduler: Exception in run handler:
Traceback (most recent call last):
  File "/opt/venvs/zuul/local/lib/python2.7/site-packages/zuul/scheduler.py", line 1019, in run
    self.process_event_queue()
  File "/opt/venvs/zuul/local/lib/python2.7/site-packages/zuul/scheduler.py", line 1093, in process_event_queue
    pipeline.manager.removeAbandonedChange(change)
  File "/opt/venvs/zuul/local/lib/python2.7/site-packages/zuul/scheduler.py", line 1409, in removeAbandonedChange
    if item.change.equals(change):
  File "/opt/venvs/zuul/local/lib/python2.7/site-packages/zuul/model.py", line 1049, in equals
    and self.ref == other.ref
AttributeError: 'PullRequest' object has no attribute 'ref'
2018-09-13 15:21:53,637 ERROR zuul.Scheduler: Exception in run handler:
Traceback (most recent call last):
  File "/opt/venvs/zuul/local/lib/python2.7/site-packages/zuul/scheduler.py", line 1019, in run
    self.process_event_queue()
  File "/opt/venvs/zuul/local/lib/python2.7/site-packages/zuul/scheduler.py", line 1093, in process_event_queue
    pipeline.manager.removeAbandonedChange(change)
  File "/opt/venvs/zuul/local/lib/python2.7/site-packages/zuul/scheduler.py", line 1409, in removeAbandonedChange
    if item.change.equals(change):
  File "/opt/venvs/zuul/local/lib/python2.7/site-packages/zuul/model.py", line 1049, in equals
    and self.ref == other.ref
AttributeError: 'PullRequest' object has no attribute 'ref'