Python 3.4's http.server large download connections are cut at ~50% mark

The issue is not present neither on Windows, nor on ReactOS Python 2.7

==== Steps to reproduce ====

1. Install Python 3.4.4
2. [As discussed in CORE-20335 ] Reboot ReactOS
3. Obtain large file (over 500 MB. For example, Windows XP ISO) and place it inside ReactOS

I used Windows XP ISO. I don't know if there's anything special about it, but I used the one available here: https://archive.org/details/en_windows_xp_professional_with_service_pack_3_x86_cd_x14-80428_202010

1. cmd -> cd <path/to/large/file's/directory>
2. python -m http.server 8000
3. From another host, attempt to download the file at `http://<reactOS_IP>:8000/largefile` (ideally with Firefox, as on error, Chrome immediately tries to redownload the file without letting the user know)
4. Observe the connection being cut at around 50% mark (different files fail at different points, for example, Windows XP ISO of size 617.756.672 bytes , failed at 308.879.360 bytes. Interestingly, Python 3.4 does not (appear) to show any problems,
   

Optionally: Retry with Python 2.7 - observe no such issue

Demonstration video: https://www.youtube.com/watch?v=2m2Pq9PQXAA