Increase entropy for 1.11's make_msgid() randint component

[Brad]

Django 1.11 copies CPython's make_msgid (​https://github.com/django/django/blob/stable/1.11.x/django/core/mail/message.py)

However, it is missing a recent change that increases the number of bits used in the random integer part of the identifier to avoid a hash collision.

Ref:

• ​https://bugs.python.org/issue6598
• ​https://github.com/python/cpython/commit/ae760c0a2ccd5557bfd915c947dfbcd3ed64fd60#diff-9150fb3cb06040b8e09b07aeae5de8c3
• ​https://hg.python.org/cpython/rev/933addbc7041

The 1.11 implementation of make_msgid() could be updated to reflect this upstream change.

Note that this does not affect Django 2.x or 3.x because they use email.utils directly.

[Brad]

PR: ​https://github.com/django/django/pull/12416

[Nick Pope]

Django 1.11 is only receiving fixes for security issues and data loss bugs. It will also be end-of-life in April 2020.

Please see the documentation regarding ​supported versions.

As of version 2.0, Django makes use of make_msgid() from the standard library (9e917cc29181ad32abc21488ee70e739ce805f3a).