Ignore last session info with a commit sequence of 0

Author: madscientist

pynuodb/encodedsession.py

@@ -283,7 +283,8 @@ def send_close(self):
     def __set_dbinfo(self, sid, txid, seqid):
         # type: (int, int, int) -> None
         with EncodedSession.__dblock:
-            lci = self.__dbinfo.get(sid, (-1, -1))
+            # 0 is an invalid sequence ID
+            lci = self.__dbinfo.get(sid, (0, 0))
             if seqid > lci[1]:
                 self.__dbinfo[sid] = (txid, seqid)