This is just hacked together real quick, not 100% production proven.

asyncio_rlock.py

import asyncio

class RLock(asyncio.Lock):
  """
  A reentrant lock for Python coroutines.
  """

  def __init__(self, *args, **kwargs):
    super().__init__(*args, **kwargs)
    self._task = None
    self._depth = 0

  @asyncio.coroutine
  def acquire(self):
    if self._task is None or self._task != asyncio.Task.current_task():
      yield from super().acquire()
      self._task = asyncio.Task.current_task()
      assert self._depth == 0
    self._depth += 1

  def release(self):
    if self._depth > 0:
      self._depth -= 1
    if self._depth == 0:
      super().release()
      self._task = None

I'm not sure why, but we need to use the @coroutine decorator for RLock.acquire() instead of the async keyword, as otherwise we'll get this error when using with await lock:

rc/player.py", line 323, in queue_song
    with await self.lock:
  File "/usr/lib/python3.5/asyncio/locks.py", line 74, in __await__
    yield from self.acquire()
TypeError: cannot 'yield from' a coroutine object in a non-coroutine generator