[PATCH 1 of 8] mail: remove code to support < Python 2.7

[Yuya Nishihara]

On Sat, 13 May 2017 12:54:33 -0700, Gregory Szorc wrote:
> # HG changeset patch
> # User Gregory Szorc <gregory.szorc at gmail.com>
> # Date 1494699164 25200
> #      Sat May 13 11:12:44 2017 -0700
> # Node ID 776aa5e07de8cab3a7382e14bf27b44dd7e9f086
> # Parent  78496ac300255e9996b3e282086661afc08af37c
> mail: remove code to support < Python 2.7

Queued with delight, thanks.