$ python3.7 repro-1725.py
Exception in thread Thread-551:
Traceback (most recent call last):
  File "/Library/Frameworks/Python.framework/Versions/3.7/lib/python3.7/threading.py", line 917, in _bootstrap_inner
    self.run()
  File "repro-1725.py", line 33, in run
    self.coll.insert_one({'num': i})
  File "/Users/shane/git/mongo-python-driver/pymongo/collection.py", line 694, in insert_one
    session=session),
  File "/Users/shane/git/mongo-python-driver/pymongo/collection.py", line 608, in _insert
    bypass_doc_val, session)
  File "/Users/shane/git/mongo-python-driver/pymongo/collection.py", line 596, in _insert_one
    acknowledged, _insert_command, session)
  File "/Users/shane/git/mongo-python-driver/pymongo/mongo_client.py", line 1329, in _retryable_write
    return self._retry_with_session(retryable, func, s, None)
  File "/Users/shane/git/mongo-python-driver/pymongo/mongo_client.py", line 1282, in _retry_with_session
    return func(session, sock_info, retryable)
  File "/Users/shane/git/mongo-python-driver/pymongo/collection.py", line 591, in _insert_command
    retryable_write=retryable_write)
  File "/Users/shane/git/mongo-python-driver/pymongo/pool.py", line 579, in command
    unacknowledged=unacknowledged)
  File "/Users/shane/git/mongo-python-driver/pymongo/network.py", line 150, in command
    parse_write_concern_error=parse_write_concern_error)
  File "/Users/shane/git/mongo-python-driver/pymongo/helpers.py", line 155, in _check_command_response
    raise OperationFailure(msg % errmsg, code, response)
pymongo.errors.OperationFailure: unable to initialize targeter for write op for collection db_11.test :: caused by :: Database db_11 not found :: caused by :: database db_11 not found

Traceback (most recent call last):
  File "repro-1725.py", line 62, in <module>
    repro()
  File "repro-1725.py", line 56, in repro
    assert t.success
AssertionError

23 Jan 19 16:23 -0800 (Connection: 104:657430200)  op_msg insert db_2 Request:{"sections":[{"payload":{"$clusterTime":{"clusterTime":{"$timestamp":{"t":1548289382,"i":191}},"signature":{"hash":{"$binary":"AI87y83wEE6V+ELmJaUtbleLSHY=","$type":"00"},"keyId":{"$numberLong":"6649842944649986060"}}},"$db":"db_2","$readPreference":{"mode":"primary"},"insert":"test","lsid":{"id":{"$binary":"srMbo3+9SlS8J+jwS2CMlg==","$type":"04"}},"ordered":true},"payloadType":0},{"payload":{"documents":[{"_id":{"$oid":"5c49056618a944e27153a1f5"},"num":0}],"identifier":"documents","size":45},"payloadType":1}]}

23 Jan 19 16:23 -0800 (Connection: 104:657430200) +118.636ms op_msg reply   Response:{"sections":[{"payload":{"$clusterTime":{"clusterTime":{"$timestamp":{"t":1548289382,"i":196}},"signature":{"hash":{"$binary":"AI87y83wEE6V+ELmJaUtbleLSHY=","$type":"00"},"keyId":{"$numberLong":"6649842944649986060"}}},"code":26,"codeName":"NamespaceNotFound","errmsg":"unable to initialize targeter for write op for collection db_2.test :: caused by :: Database db_2 not found :: caused by :: database db_2 not found","ok":0.0,"operationTime":{"$timestamp":{"t":1548289382,"i":194}}},"payloadType":0}]}