Incorrect counting of pending messages in OutboundTcpConnection

Somehow OutboundTcpConnection.getPendingMessages() seems to return a wrong number.

nodetool netstats
Mode: NORMAL
Not sending any streams.
Read Repair Statistics:
Attempted: 1655
Mismatch (Blocking): 0
Mismatch (Background): 2
Pool Name                    Active   Pending      Completed
Large messages                  n/a         5              0
Small messages                  n/a         0       31534100
Gossip messages                 n/a         0         520393

Inspection of the heap dump of that node unveiled that all instances of OutboundTcpConnection.backlog are empty but currentMsgBufferCount is 1 for 5 instances of OutboundTcpConnection.

Maybe the cause is in OutboundTcpConnection.run() where drainedMessages.size() is called twice but assumed that these are equal.

/cc aweisberg