The test shows the issue.
It seems that Consumer.needAck() for AckExplicit should consider
that an Ack is needed if sseq > o.asflr and there is no pending
ack at all. However making this change would break the test
TestJetStreamInterestRetentionStream.
Also, running the new test with `-count 100` and by adding an
artificial delay in stream.ackMsg() (just before calling
mset.store.RemoveMsg(seq)) causes sometimes delete requests
for the same sequence to be processed twice, which causes
the new test to fail (even with an attempted fix as discussed
above). I think that the attempt to remove the same sequence twice
is messing up the state.
Signed-off-by: Ivan Kozlovic <ivan@synadia.com>
eff27e26be