Deploy breaks Drupal 6 to 7 upgrade when using drush

I'm upgrading Drupal 6 to 7 via drush (drush -l my.local -v updb) and Deploy module is disabled in my environment.
Even then, it's messing around by executing full Drupal bootstrap for update process.

Backtrace:

Array
(
    [0] => Array
        (
            [file] => includes/bootstrap.inc
            [line] => 1929
            [function] => drupal_is_denied
            [args] => Array
                (
                    [0] => 127.0.0.1
                )

        )

    [1] => Array
        (
            [file] => includes/bootstrap.inc
            [line] => 2338
            [function] => drupal_block_denied
            [args] => Array
                (
                    [0] => 127.0.0.1
                )

        )

    [2] => Array
        (
            [file] => includes/bootstrap.inc
            [line] => 2193
            [function] => _drupal_bootstrap_page_cache
            [args] => Array
                (
                )

        )

    [3] => Array
        (
            [file] => sites/all/modules/contrib/deploy/includes/deploy.drush.inc
            [line] => 14
            [function] => drupal_bootstrap
            [args] => Array
                (
                    [0] => 7
                )

        )

    [4] => Array
        (
            [file] => /usr/local/Cellar/drush/6.1.0/libexec/includes/command.inc
            [line] => 975
            [function] => deploy_drush_command
            [args] => Array
                (
                )

        )

Code:

function deploy_drush_command() {
  // Drupal isn't bootstraped long enough, when this hook is fired, to find out
  // what authentication methods and options that are available. So we must
  // execute the full bootstrap here. Sorry for that.
  drupal_bootstrap(DRUPAL_BOOTSTRAP_FULL);

Removing temporary Deploy module from the filesystem seems to do the workaround.

Related:
#517742: Upgrade failing if blocked_ips doesn't exist