[2.4b3] traceback while enlisting

I'm seeing this in the regiond.log every time a system contacts the MAAS server as part of network booting. The enlistment continues successfully.

2018-05-08 16:06:48 maasserver.utils.dbtasks: [critical] Unhandled failure in database task.
 Traceback (most recent call last):
   File "/usr/lib/python3.6/threading.py", line 864, in run
     self._target(*self._args, **self._kwargs)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 850, in worker
     return target()
   File "/usr/lib/python3/dist-packages/twisted/_threads/_threadworker.py", line 46, in work
     task()
   File "/usr/lib/python3/dist-packages/twisted/_threads/_team.py", line 190, in doWork
     task()
 --- <exception caught here> ---
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 250, in inContext
     result = inContext.theWork()
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 266, in <lambda>
     inContext.theWork = lambda: context.call(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 122, in callWithContext
     return self.currentContext().callWithContext(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 85, in callWithContext
     return func(*args,**kw)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 883, in callInContext
     return func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 232, in wrapper
     result = func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 756, in call_within_transaction
     return func_outside_txn(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 563, in retrier
     return func(*args, **kwargs)
   File "/usr/lib/python3.6/contextlib.py", line 52, in inner
     return func(*args, **kwds)
   File "/usr/lib/python3/dist-packages/maasserver/rpc/events.py", line 88, in send_event_mac_address
     "address '%s'.", type_name, description, mac_address)
 builtins.TypeError: debug() takes from 1 to 2 positional arguments but 5 were given

2018-05-08 16:06:48 maasserver.utils.dbtasks: [critical] Unhandled failure in database task.
 Traceback (most recent call last):
   File "/usr/lib/python3.6/threading.py", line 864, in run
     self._target(*self._args, **self._kwargs)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 850, in worker
     return target()
   File "/usr/lib/python3/dist-packages/twisted/_threads/_threadworker.py", line 46, in work
     task()
   File "/usr/lib/python3/dist-packages/twisted/_threads/_team.py", line 190, in doWork
     task()
 --- <exception caught here> ---
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 250, in inContext
     result = inContext.theWork()
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 266, in <lambda>
     inContext.theWork = lambda: context.call(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 122, in callWithContext
     return self.currentContext().callWithContext(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 85, in callWithContext
     return func(*args,**kw)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 883, in callInContext
     return func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 232, in wrapper
     result = func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 756, in call_within_transaction
     return func_outside_txn(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 563, in retrier
     return func(*args, **kwargs)
   File "/usr/lib/python3.6/contextlib.py", line 52, in inner
     return func(*args, **kwds)
   File "/usr/lib/python3/dist-packages/maasserver/rpc/events.py", line 88, in send_event_mac_address
     "address '%s'.", type_name, description, mac_address)
 builtins.TypeError: debug() takes from 1 to 2 positional arguments but 5 were given

2018-05-08 16:06:49 maasserver.utils.dbtasks: [critical] Unhandled failure in database task.
 Traceback (most recent call last):
   File "/usr/lib/python3.6/threading.py", line 864, in run
     self._target(*self._args, **self._kwargs)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 850, in worker
     return target()
   File "/usr/lib/python3/dist-packages/twisted/_threads/_threadworker.py", line 46, in work
     task()
   File "/usr/lib/python3/dist-packages/twisted/_threads/_team.py", line 190, in doWork
     task()
 --- <exception caught here> ---
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 250, in inContext
     result = inContext.theWork()
   File "/usr/lib/python3/dist-packages/twisted/python/threadpool.py", line 266, in <lambda>
     inContext.theWork = lambda: context.call(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 122, in callWithContext
     return self.currentContext().callWithContext(ctx, func, *args, **kw)
   File "/usr/lib/python3/dist-packages/twisted/python/context.py", line 85, in callWithContext
     return func(*args,**kw)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 883, in callInContext
     return func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/provisioningserver/utils/twisted.py", line 232, in wrapper
     result = func(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 756, in call_within_transaction
     return func_outside_txn(*args, **kwargs)
   File "/usr/lib/python3/dist-packages/maasserver/utils/orm.py", line 563, in retrier
     return func(*args, **kwargs)
   File "/usr/lib/python3.6/contextlib.py", line 52, in inner
     return func(*args, **kwds)
   File "/usr/lib/python3/dist-packages/maasserver/rpc/events.py", line 88, in send_event_mac_address
     "address '%s'.", type_name, description, mac_address)
 builtins.TypeError: debug() takes from 1 to 2 positional arguments but 5 were given