Running gdbserver as a `preLaunchTask` - need to press start/stop button several times

• VSCode Version: Code 1.14.0 (b8cd5b9556d8b70ea560d35b903422363f6c5c40, 2017-07-10T20:36:40.018Z)
• OS Version: Linux x64 4.4.0-53-generic
• Extensions:

Hello. Thank you for the great tool - I'm using vscode/cpptools everyday and happy with it.

Now to the problem. I have the following task in tasks.json:

{
    "taskName": "docker build&run",
    "linux": {
        "args": [
            "\"docker run --rm --privileged -p 2222:2222 -v ~/path/:/path/ -w /path/build cpp_tools bash -c 'cmake --build . && gdbserver localhost:2222 ./app'\""
        ]
    },
    "group": {
        "kind": "build",
        "isDefault": true
    }
}

As you can see, it starts a docker container that builds an executable and runs gdbserver inside.

Here's my launch.json:

{
    "version": "0.2.0",
    "configurations": [
        {
            "name": "(gdb) remote",
            "type": "cppdbg",
            "request": "launch",
            "preLaunchTask": "docker build&run",
            "program": "${workspaceRoot}/build/app",
            "args": [],
            "stopAtEntry": false,
            "cwd": "${workspaceRoot}/build",
            "environment": [],
            "externalConsole": true,
            "MIMode": "gdb",
            "miDebuggerServerAddress": "localhost:2222",
            "sourceFileMap": {
                "/path/": "~/path/"
            },
            "setupCommands": [
                {
                    "description": "Enable pretty-printing for gdb",
                    "text": "-enable-pretty-printing",
                    "ignoreFailures": true
                }
            ]
        }
    ]
}

I want to build an app and start the debug session with F5 button. The problem is that I need to press F5 twice - the first press builds an app and starts the debug server in docker container and the second press launches my application (which successfully connects). The problem appears both for F5 and Start Debugging button in GUI.
Also I have to press stop button 3 (three) times in order to stop an application (both for Shift+F5 and the Stop button in GUI).

Reproduce the behavior using the tasks.json and launch.json configurations, pressing F5 and then stopping the session as described. Start by tracing the preLaunchTask and debug-session lifecycle in the extension; done means one F5 starts the task and debugger, and one stop action ends the application and server.