drush_valid_drupal_root() requires only a file called includes/common.inc to match a Drupal directory, which causes problems when this file pattern appears elsewhere, in non-Drupal root contexts (e.g. in module_builder module).
Refactor drush_valid_drupal_root() to avoid a second function with checks.
Make _drush_add_commandfiles() more robust at detecting and avoiding double-loading Drush commandfiles.
Fix bug in drush_tarball_extract that caused the wrong thing to be returned in the file list if $destination was specified when a zip file was extracted.
use drush_op() instead of call_user_func()
Get version and compatibility constants for Drupal 8. See http://drupal.org/node/2067017.
Removed configuratibility of pathname in test report xml files.

The filename is output as relative pathname.