db-url is added as command-line option in drush_invoke_process()

I've been using drush_invoke_process() extensively in Drush Rebuild. All worked well with 8.x-6.0-beta1. With 8.x-6.0-rc1 (and the latest dev), the db-url parameter from the site alias passed to drush_invoke_process() is added as a command-line option, causing drush_invoke_process() to fail.

I'm not sure if I am supposed to call drush_invoke_process() differently or if this is a bug. I did find that if I pass 'method' => 'POST' as a backend option, the call succeeds.

For example, with 'method' => 'GET' (default):

    drush_invoke_process($this->environment, 'site-alias', array($source), array('short' => TRUE), array('integrate' => FALSE));

Backend invoke: /usr/local/bin/php -d memory_limit="512M" -d error_reporting="E_ALL|E_NOTICE|E_STRICT" -d      [command]
display_errors="stderr"  /Users/kosta/src/drupal/drush/drush.php --php=/usr/local/bin/php --php-options='-d
memory_limit="512M" -d error_reporting="E_ALL|E_NOTICE|E_STRICT" -d display_errors="stderr" '  --backend=2
--verbose --debug --root=/Users/kosta/src/site/docroot --uri=http://local.example.com
site-alias '@example.prod'   --short --db-url='mysql://root@127.0.0.1/example_local' 2>&1 [2.66 sec, 21.51 MB]
/usr/local/bin/php -d memory_limit="512M" -d error_reporting="E_ALL|E_NOTICE|E_STRICT" -d                       [notice]
display_errors="stderr"  /Users/kosta/src/drupal/drush/drush.php --php=/usr/local/bin/php --php-options='-d
memory_limit="512M" -d error_reporting="E_ALL|E_NOTICE|E_STRICT" -d display_errors="stderr" '  --backend=2
--verbose --debug --root=/Users/kosta/src/example/docroot --uri=http://local.ipihd.org
site-alias '@example.prod'   --short --db-url='mysql://root@127.0.0.1/example_local' 2>&1 [2.66 sec, 21.52 MB]

With 'method' => 'POST':

    drush_invoke_process($this->environment, 'site-alias', array($source), array('short' => TRUE), array('integrate' => FALSE, 'method' => 'POST'));

Backend invoke: /usr/local/bin/php -d memory_limit="512M" -d error_reporting="E_ALL|E_NOTICE|E_STRICT" -d      [command]
display_errors="stderr"  /Users/kosta/src/drupal/drush/drush.php --php=/usr/local/bin/php --php-options='-d
memory_limit="512M" -d error_reporting="E_ALL|E_NOTICE|E_STRICT" -d display_errors="stderr" '  --backend=2
--root=/Users/kosta/src/example/docroot --uri=http://local.example.com  site-alias
'@example.prod' 2>&1 [2.52 sec, 21.51 MB]
/usr/local/bin/php -d memory_limit="512M" -d error_reporting="E_ALL|E_NOTICE|E_STRICT" -d                       [notice]
display_errors="stderr"  /Users/kosta/src/drupal/drush/drush.php --php=/usr/local/bin/php --php-options='-d
memory_limit="512M" -d error_reporting="E_ALL|E_NOTICE|E_STRICT" -d display_errors="stderr" '  --backend=2
--root=/Users/kosta/src/example/docroot --uri=http://local.example.com  site-alias
'@example.prod' 2>&1 [2.52 sec, 21.52 MB]