Raven not reporting django/python SystemError?

I am getting a SystemError in a django view but somehow it is not reported by raven/sentry.

I know the error I am getting because my view returns a JSONResponse which includes the error from the exception handler in my code. I then disabled sentry logging (configured as in the example in https://docs.sentry.io/clients/python/integrations/django/#integration-with-logging) and got a traceback in the server logs:
SystemExit: 1

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File “xxviews.py”, line 176, in myview
File “xxmodels.py”, line 640, in save
<line above recurses 9 times>
total = myobj.xx_set.exclude(pk=self.pk).aggregate(paid=Sum(‘amount’))[‘paid’] or 0
File “…python3.5/site-packages/django/db/models/query.py”, line 356, in aggregate
return query.get_aggregation(self.db, kwargs.keys())
File “…python3.5/site-packages/django/db/models/sql/query.py”, line 457, in get_aggregation
result = compiler.execute_sql(SINGLE)
File “…python3.5/site-packages/django/db/models/sql/compiler.py”, line 835, in execute_sql
cursor.execute(sql, params)
File “…python3.5/site-packages/raven/contrib/django/client.py”, line 114, in execute
return real_execute(self, sql, params)
File “…python3.5/site-packages/django/db/backends/utils.py”, line 64, in execute
return self.cursor.execute(sql, params)
File “…python3.5/encodings/utf_8.py”, line 16, in decode
return codecs.utf_8_decode(input, errors, True)
SystemError: returned a result with an error set

The error I am getting is not the topic of this question, but rather: why is raven not reporting the error? My query times out at 30 seconds and I get a:
DEBUG 2017-04-26 13:09:21,468 base 54479 140303536756480 Configuring Raven for host: <raven.conf.remote.RemoteConfig object at 0x7f9aee2204e0> [2017-04-26 13:09:51 +0000] [54471] [CRITICAL] WORKER TIMEOUT (pid:54479)

It feels like raven is crashing. Is a SystemError beyond the reach of raven or am I missing something (everything else is working well, I get my other errors in Sentry)?