Not sure how old your experience is, but I tested from Python via epoll a few minutes after posting (never used that option before!) and it worked as described.
Behind the scenes, Python may have another layer in there to check the socket options, etc, before returning. ie: Just because it looks like it's working on the Python level doesn't mean it's working the same way underneath.
Do you have a link to either an announcement of this change, or C code that demonstrates it? If it has changed, I might start doing some things differently...
I dealt with all of this in 2015, and spent three months trying to get epoll to perform similarly to kqueue; namely, to avoid returning on any and every packet received and, preferably, to abide by some sort of minimum bytes received (or connection closing) before returning.
Unless I'm missing something (and I could very well be missing something), I'm not seeing how that is any different than anything I tried...and I went through every socket option I could find, even if it seemed irrelevant.
Have you written code that actually performs this way? Or are you speculating? I really do wish I could do this with epoll, but I (and several others) just never were able to figure it out. And kqueue simply performed at least an order of magnitude better of any variation I could hack together with epoll.
I had neither written code to test it nor was speculating - I was reading the kernel source, which is pretty clear (if you know in general how file polling is implemented in the Linux kernel).
