v1.2.1 version bump (same code as '1.2+3+g42786a6')

Stable release - designed for v17.x / Debian Bullseye.

Last py2 version.

==================

v1.0 Release Notes
==================

In use, stable and bug-free for nearly 3 quarters.

Usage::

    Syntax: deckdebuild [-options] /path/to/buildroot [ /path/to/output-dir ]
    build a Debian package in a decked chroot

    Output dir defaults to ../

    Resolution order for options:
    1) command line (highest precedence)
    2) environment variable
    3) configuration file (/etc/deckdebuild.conf)
    4) built-in default (lowest precedence)

    Options:
      -r --root-cmd=         command userd to gain root_privileges
                             environment: DECKDEBUILD_ROOT_CMD
                             default: fakeroot

      -u --user=             build username (created if it doesn't exist)
                             environment: DECKDEBUILD_USER
                             default: build

      -p --preserve-build    don't remove build deck after build
                             environment: DECKDEBUILD_PRESERVE_BUILD
                             default: False

    Protected options (root only):

      --satisfydepends-cmd=  program used to satisfy build dependencies
                             environment: DECKDEBUILD_SATISFYDEPENDS_CMD
                             default: /usr/lib/pbuilder/pbuilder-satisfydepends

      --vardir=              var data path
                             environment: DECKDEBUILD_VARDIR
                             default: /var/lib/deckdebuild

    Configuration file format (/etc/deckdebuild.conf):

      <option-name> <value>