How confident are we that this is a regression from the coroutine origin tracking changes? (I'd double-check myself, but my cpython checkout is tied up for the next few hours doing --enable-optimizations builds.)

Looking at @asyncio.coroutine, in particular this branch that gets taken when debug mode is enabled:

https://github.com/python/cpython/blob/6b273f7f4056f8276f61a97c789d6bb4425e653c/Lib/asyncio/coroutines.py#L135-L149

I'm not seeing anything that would toggle the CO_ITERABLE_COROUTINE flag, and if I use pdb I can see that in the broken test the 'sleeper' function indeed doesn't have that flag set. But I didn't touch that code in the origin tracking patch, which makes me think that the proximal cause here might have been 5f841b553814969220b096a2b4f959b7f6fcbaf6 ?