Issue #1409682 by axel.rutz - Provide drush option to flush the registry before rebuilding.
Issue #1951098 by amsri - More strict Drupal core version check to avoid warnings.
Issue #1974354 by Cottser - Drupal 8 - Fix for Call to undefined method Drupal\Core\Cache\DatabaseBackend::flush()
Add more verbose and precise drush_log entries.
Issue #1971684 by stewsnooze, mkalkbrenner, Spleshka - Registry rebuild does not work with non core lock.inc
Issue #1971684 by stewsnooze, mkalkbrenner, Spleshka - Registry rebuild does not work with non core lock.inc - registry_rebuild.php version.
There is no drush_log in the script version.
Improve messages in registry_rebuild.php