Filters from "latest" to "latest" always return empty list

[4gn3s]

Package versions:
eth-testrpc: 0.8.7
ethereum-tester-client: 1.2.5
geth: 1.5.3, 1.5.4

What was wrong?

When using filters, if filter has {"fromBlock": "latest", "toBlock": "latest"} (to retrieve logs from the most recently mined transaction), testrpc returns an empty list, while geth returns a correct log.
A minimal example which shows the current behaviour:

import pytest
from eth_tester_client.utils import encode_address
from ethereum import tester


@pytest.fixture(params=[
    'testrpc',
    'temp',
])
def chain(project, request):
    with project.get_chain(request.param) as chain:
        if request.param == 'temp':
            address = chain.web3.personal.importRawKey(tester.keys[0], "")
            assert address == encode_address(tester.accounts[0])
            chain.web3.personal.unlockAccount(address, "", duration=0)
            chain.wait.for_unlock(address)
        yield chain


def deploy(chain, contract_name):
    contract_factory = chain.get_contract_factory(contract_name)
    deploy_txn_hash = contract_factory.deploy()
    deploy_address = chain.wait.for_contract_address(deploy_txn_hash, timeout=120)
    return contract_factory(address=deploy_address)


def test_latest_logs(chain):
    contract = deploy(chain, 'TestContract')
    event_filter = contract.pastEvents('TestEvent', {"fromBlock": "latest",
                                                     "toBlock": "latest"})
    txn_hash = contract.transact().do_action(1234)
    chain.wait.for_receipt(txn_hash)
    event_logs = event_filter.get()
    assert event_logs
    event_logs = filter(lambda log: log["transactionHash"] == txn_hash, event_logs)
    assert len([e["args"] for e in event_logs]) > 0

and the TestContract.sol:

contract TestContract {
    event TestEvent(uint value);
    function do_action(uint value){
        TestEvent(value);
    }
}

When running, I get:

____ test_latest_logs[testrpc] ____

chain = <populus.chain.TestRPCChain object at 0x7fa413aa0f50>

    def test_latest_logs(chain):
        contract = deploy(chain, 'TestContract')
        event_filter = contract.pastEvents('TestEvent', {"fromBlock": "latest",
                                                         "toBlock": "latest"})
        txn_hash = contract.transact().do_action(1234)
        chain.wait.for_receipt(txn_hash)
        event_logs = event_filter.get()
>       assert event_logs
E       assert []

tests/unit/testrpc_bug_logs.py:43: AssertionError

...

===== 1 failed, 1 passed in 13.80 seconds =====

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