py3: don?t subscript socket.error On Python 2, socket.error was subscriptable. On Python 3, socket.error is an alias to OSError and is not subscriptable. The except block passes the exception to self.send_error(). This fails on both Python 2 (if it was executed) and Python 3, as it expects a string. Getting the attribute .strerror works on Python 2 and Python 3, and has the same effect as the previous code on Python 2.

from __future__ import absolute_import, print_function

import sys

for line in sys.stdin:
    if line.lower() in ("message-id: \n", "in-reply-to: \n"):
        line = line[:-2]
    print(line, end="")