Description of problem:

When a consumer releases a message, the consumer gets in the next fetch() call  the next oldest message, either from the free group or from one of the groups it already owns. But calling the fetch() method once again causes the released message to be redelivered. This actually causes a failure in the message consumption order. 

This is also in conflict with MRG/M UG: "A subscriber might choose not to take ownership of an acquired message. In this case, the message is released. This allows the broker to re-deliver the message to any other available subscriber - this can include the subscriber that just released the message.

NOTE: the same behaviour can be seen using transaction as well. I suppose it is the same issue, but this needs to be tested as well.

in example:

queue: HEAD-> A0,B1,A2,A3

receiver_1 releases A0, then gets B1... then gets A0 on its next fetch.

OR

receiver_1 consumes A0 and do a rollback(), then gets B1... then gets A0 on its next fetch. 

Version-Release number of selected component (if applicable):
python-qpid-0.14-1.el5
python-qpid-qmf-0.14-2.el5
qpid-cpp-client-0.14-3.el5
qpid-cpp-client-devel-0.14-3.el5
qpid-cpp-client-devel-docs-0.14-3.el5
qpid-cpp-client-ssl-0.14-3.el5
qpid-cpp-server-0.14-3.el5
qpid-cpp-server-cluster-0.14-3.el5
qpid-cpp-server-devel-0.14-3.el5
qpid-cpp-server-ssl-0.14-3.el5
qpid-cpp-server-store-0.14-3.el5
qpid-cpp-server-xml-0.14-3.el5
qpid-java-client-0.14-1.el5
qpid-java-common-0.14-1.el5
qpid-java-example-0.14-1.el5
qpid-qmf-0.14-2.el5
qpid-qmf-devel-0.14-2.el5
qpid-tests-0.14-1.el5
qpid-tools-0.14-1.el5


How reproducible:
100%

Steps to Reproduce:
1. run the attached reproducer for "released messages" without an argument
(this demonstrates behaviour on common queue)
2. run the attached reproducer for "released messages" with an argument specified (this demonstrates behaviour on message group queue)
3. check results

AND

1. run the attached reproducer for "transactions" without an argument
(this demonstrates behaviour on common queue)
2. run the attached reproducer for "transactions" with an argument specified (this demonstrates behaviour on message group queue)
3. check results
  
Actual results:
releasing a message cause consumption order discrepancies

Expected results:
releasing a message do not cause consumption order discrepancies
released message can be immediately re-fetched by the same consumer

Additional info:

Reproducers output:

# ./test_released.py 
queueing message: Message('Message0')
queueing message: Message('Message1')
queueing message: Message('Message2')
queueing message: Message('Message3')

receiver_1: Message(properties={'x-amqp-0-10.routing-key': u'example'}, content='Message0')
receiver_1: Message(redelivered=True, properties={'x-amqp-0-10.routing-key': u'example'}, content='Message0')
receiver_1: Message(properties={'x-amqp-0-10.routing-key': u'example'}, content='Message1')
receiver_2: Message(properties={'x-amqp-0-10.routing-key': u'example'}, content='Message2')
receiver_2: Message(properties={'x-amqp-0-10.routing-key': u'example'}, content='Message3')

# ./test_released.py message_groups
queueing message: Message('Message0')
queueing message: Message('Message1')
queueing message: Message('Message2')
queueing message: Message('Message3')

receiver_1: Message(properties={u'GROUP-KEY': u'A', 'x-amqp-0-10.routing-key': u'example'}, content='Message0')
receiver_1: Message(properties={u'GROUP-KEY': u'B', 'x-amqp-0-10.routing-key': u'example'}, content='Message1')
receiver_1: Message(redelivered=True, properties={u'GROUP-KEY': u'A', 'x-amqp-0-10.routing-key': u'example'}, content='Message0')
receiver_2: Message(properties={u'GROUP-KEY': u'A', 'x-amqp-0-10.routing-key': u'example'}, content='Message2')
receiver_2: Message(properties={u'GROUP-KEY': u'A', 'x-amqp-0-10.routing-key': u'example'}, content='Message3')

# ./test_transactions.py 
queueing message: Message('None0')
queueing message: Message('None1')
queueing message: Message('None2')
queueing message: Message('None3')

receiver_1: Message(properties={'x-amqp-0-10.routing-key': u'example'}, content='None0')
receiver_1: Message(redelivered=True, properties={'x-amqp-0-10.routing-key': u'example'}, content='None0')
receiver_1: Message(properties={'x-amqp-0-10.routing-key': u'example'}, content='None1')
receiver_1: Message(properties={'x-amqp-0-10.routing-key': u'example'}, content='None2')
receiver_1: Message(properties={'x-amqp-0-10.routing-key': u'example'}, content='None3')

# ./test_transactions.py message_groups
queueing message: Message(properties={'GROUP-KEY': 'A'}, content='Message-A0')
queueing message: Message(properties={'GROUP-KEY': 'B'}, content='Message-B1')
queueing message: Message(properties={'GROUP-KEY': 'A'}, content='Message-A2')
queueing message: Message(properties={'GROUP-KEY': 'A'}, content='Message-A3')

receiver_1: Message(properties={u'GROUP-KEY': u'A', 'x-amqp-0-10.routing-key': u'example'}, content='Message-A0')
receiver_1: Message(properties={u'GROUP-KEY': u'B', 'x-amqp-0-10.routing-key': u'example'}, content='Message-B1')
receiver_1: Message(redelivered=True, properties={u'GROUP-KEY': u'A', 'x-amqp-0-10.routing-key': u'example'}, content='Message-A0')
receiver_1: Message(properties={u'GROUP-KEY': u'A', 'x-amqp-0-10.routing-key': u'example'}, content='Message-A2')
receiver_1: Message(properties={u'GROUP-KEY': u'A', 'x-amqp-0-10.routing-key': u'example'}, content='Message-A3')