Possible dbussy ravel listen_signal bug?

foo-dbus.conf

<!DOCTYPE busconfig PUBLIC
          "-//freedesktop//DTD D-BUS Bus Configuration 1.0//EN"
          "http://www.freedesktop.org/standards/dbus/1.0/busconfig.dtd">
<!-- store in /etc/dbus-1/system.d -->
<busconfig>
  <policy user="root">
    <allow own="com.foo"/>
  </policy>
  <policy context="default">
    <allow send_destination="com.foo"/>
    <allow receive_sender="com.foo"/>
  </policy>
</busconfig>

foo.py

import asyncio
import ravel
from dbussy import DBUS

"""
This script runs using the DBus bus name "com.foo".

It serves the path /com/Foo, while listening to /org/freedesktop/NetworkManager.

The NetworkManager paths are showing up in the com.foo bus space, with the
three standard DBus interfaces. Is this a bug?

See https://github.com/ldo/dbussy/issues/27
"""

bus = ravel.system_bus()
loop = asyncio.get_event_loop()

bus.attach_asyncio(loop)
bus.request_name(bus_name="com.foo", flags=DBUS.NAME_FLAG_DO_NOT_QUEUE)


@ravel.interface(ravel.INTERFACE.SERVER, name="com.foo")
class FooInterface:
    @ravel.method(
        name="Foo",
        in_signature="",
        out_signature="",
    )
    def foo(self):
        pass


foo = FooInterface()
bus.register("/com/Foo", fallback=False, interface=foo)


@ravel.signal(name="DeviceRemoved", in_signature="o")
def device_rm(nm_path):
    print("{} removed".format(nm_path))


ravel.system_bus().listen_signal(
    path="/org/freedesktop/NetworkManager",
    fallback=False,
    interface="org.freedesktop.NetworkManager",
    name="DeviceRemoved",
    func=device_rm,
)

loop.run_forever()