asyncio.wait_for is coroutine itself, to start executing code, no matter with this PR or not it needs to be awaited/yield from

import asyncio

@asyncio.coroutine
def foo():
    print(1)

loop = asyncio.get_event_loop()

fut = asyncio.wait_for(foo(), 0)

print('it is not raised yet')

try:
    loop.run_until_complete(fut)
except asyncio.TimeoutError:
    print('raised here')


will print 
it is not raised yet
raised here