cocotb 1.40 freeze bug with Verilator

Makefile

TOPLEVEL_LANG = verilog
VERILOG_SOURCES = $(shell pwd)/test.v
TOPLEVEL = thing
MODULE = test
SIM ?= verilator

include $(shell cocotb-config --makefiles)/Makefile.sim

test.py

import cocotb
from cocotb.clock import Clock, Timer
from cocotb.monitors.avalon import AvalonSTPkts as AvalonSTMonitor
from cocotb.triggers import RisingEdge

async def new(dut):
    rx_clock = Clock(dut.rx_clk, 10, units='us')
    tx_clock = Clock(dut.tx_clk, 10, units='us')
    cocotb.fork(rx_clock.start())
    cocotb.fork(tx_clock.start())
    # This works
    # _ = AvalonSTMonitor(dut, 'st_out', dut.rx_clk)
    await Timer(50, units='us')
    # This freezes
    _ = AvalonSTMonitor(dut, 'st_out', dut.rx_clk)

@cocotb.test()
async def test_a(dut):
    await new(dut)
    await RisingEdge(dut.tx_clk)

@cocotb.test()
async def test_b(dut):
    await new(dut)
    await RisingEdge(dut.tx_clk)

test.v

`timescale 1 us / 1 us
module thing (
    input  wire tx_clk,
    input  wire rx_clk,
    input  wire reset,

    output wire [7:0] st_out_data,
    output wire       st_out_valid,
    output wire       st_out_startofpacket,
    output wire       st_out_endofpacket,
    output wire       st_out_empty
  );
endmodule