Deferred promise does not handle reject

[DmitryPorotov]

This is my code:

from promise import Promise
from threading import Timer
from time import sleep


class MyClass:
    def __init__(self):
	self.p = None

    def get_promise(self):
	self.p = Promise()

	def reject():
	    self.p.reject(Exception("qwe"))

	def resolve():
	    self.p.fulfill("asd")

	Timer(3, reject).start()
	return self.p


i = MyClass()


def on_resolve(x):
    print(str(x))


def on_reject(x):
    print(str(x))


p = i.get_promise()
p.then(on_resolve, on_reject)

while 1:
    sleep(1)

on_reject is never called in the master branch version (2.1.0). But it works fine in 1.0.1.
I've stepped through execution and I think I might have found the problem. I saw that the code goes to this function:

def _reject(self, reason, traceback=None):
    self._state = STATE_REJECTED
    self._fulfillment_handler0 = reason
    self._traceback = traceback

    if self._is_final:
        assert self._length == 0
        return async_instance.fatal_error(reason)

    if self._length > 0:
        async_instance.settle_promises(self)
    else:
        self._ensure_possible_rejection_handled()  # the execution goes here

    if self._is_async_guaranteed:
        self._settle_promises()
    else:
        async_instance.settle_promises(self)

But _ensure_possible_rejection_handled does nothing:

def _ensure_possible_rejection_handled(self):
    # self._rejection_is_unhandled = True
    # async_instance.invoke_later(self._notify_unhandled_rejection, self)
    pass

Is it a bug or am I doing something wrong?