Merge from 3.1: Issue #13703: add a way to randomize the hash values of basic types (str, bytes, datetime)
in order to make algorithmic complexity attacks on (e.g.) web apps much more complicated.

The environment variable PYTHONHASHSEED and the new command line flag -R control this
behavior.

in order to make algorithmic complexity attacks on (e.g.) web apps much more complicated.

The environment variable PYTHONHASHSEED and the new command line flag -R control this
behavior.

Also wrap two looong lines.

upon malformed POST request.

upon malformed POST request.

to to makes bytes mutable, before deciding to add bytearrays.)

Closes #11689.

Closes #13995.

Initial patch by Johannes Vogel.

Patch by Hynek Schlawack.

Patch by Suman Saha.

Patch by Suman Saha.

Issue #10287: nntplib now queries the server's CAPABILITIES first before sending MODE READER, and only sends it if not already in READER mode.
Patch by Hynek Schlawack.