I straced both chromium and Python during the issue and seen this:

Chromium open a socket (port 55084), sends "GET /domain1.html" to it.
Python accepts it, reads "GET /domain1.html", replies, OK
Chromium closes socket on port 55084
Chromium opens three sockets:
  - port 55086
  - port 55088
  - port 55090
Python accepts a socket on port 55088 and read on it (blocking)
Chromium writes "GET /domain2.html" on socket on port 55090

At this point we're stuck, three socket are opened, Python is reading on one of them, Chromium is writing on another.