<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def login_honeypot(request):
 """ A login honypot. """

    status_code = None
    if request.method == 'POST':
        form = HoneypotForm(request.POST)
        if form.is_valid():
            username = form.cleaned_data["username"]
            password = form.cleaned_data["password"]

            # Don't store password from existing users:
            if request.user.is_authenticated(): # Logged in user used the honypot?!?
                password="***"
            else:
                user_model = get_user_model()
                existing_user = user_model.objects.filter(username=username).exists()
                if existing_user:
                    password="***"

            HonypotAuth.objects.add(request, username, password)

            # Send a "errored" form back, that looks like the normal form
            form = HoneypotForm(request.POST, raise_error=True)
            status_code = 401 # Unauthorized
    else:
        form = HoneypotForm()
    context = {
        "form": form,
        "form_url": request.path,
    }

    response = render_to_response(
        "admin/login.html",
        context, context_instance=RequestContext(request)
    )
    if status_code is not None:
        response.status_code = status_code
    return response