Rocky.Context.sendToAll sends a response not to all open requests

[dbukhmastov]

Scenario:

local numberOfRequests = 6;
local app = Rocky({"timeout": 6});
local count = 0;
app.on("GET", "/test", function(context) {
    // do nothing
}.bindenv(this));
imp.wakeup(0, function() {
    for (local i = 0; i < numberOfRequests; i++) {
        local req = http.request("GET", http.agenturl() + "/test", {}, "body");
        req.sendasync(function(res) {
            server.log("Response #" + (++count) + " | statuscode=" + res.statuscode);
        }.bindenv(this));
    }   
}.bindenv(this));
imp.wakeup(2, function() {
    Rocky.sendToAll(200, {"message": "OK"});
    imp.wakeup(2, function() {
        server.log("Total responses: " + count + "/" + numberOfRequests);
    }.bindenv(this));
}.bindenv(this));

Log:

[Agent] Response #1 | statuscode=200
[Agent] Response #2 | statuscode=200
[Agent] Response #3 | statuscode=200
[Agent] Response #4 | statuscode=200
[Agent] Total responses: 4/6
[Agent] Response #5 | statuscode=500
[Agent] Response #6 | statuscode=500

Tests:

This issue affects class: tests/AsyncRequests.agent.test.nut method: testMultipleAsyncRequestsWithSendToAll()