Issuing "TestRequest" while processing results of "ResendRequest" causes timeout/disconnect

[BrianCameronBooth]

SCENARIO:

1. Client connects and processes messages normally for a period of time.
2. Client is disconnected for whatever reason (network outage, process termination etc)
3. Client initiates connection sometime later.
4. Client recognizes MsgSeqNum is "too high" on incoming messages and issues a ResendRequest.
5. Older messages start arriving to satisfy the "ResendRequest" while at the same time new messages are arriving.
6. All new messages are queued while NextTargetMsgSeqNum is incremented by incoming PossDupFlag=Y messages.
7. At some point client decides it is time for a "TestRequest"
8. The resulting "Heartbeat" response arrives immediately but is reported to have a MsgSeqNum that is "too high".
9. Becaues of the sequence number being too high, the "Heartbeat" response is also queued plus SessionState.LastReceivedTimeDT is not updated.
10. The alloted time for processing the Heartbeat response elapses
11. The client then calls Session.Disconnect("Timed out waiting for heartbeat");
12. Repeat steps 3-11 potentially multiple times before the session becomes stable.

POTENTIAL FIX:
Don't queue heartbeat responses?