This release is contains a bunch of bug fixes, and supports new features coming in tomorrow's Drupal 8.6 release ([#3625]).
- Fix #3595. Remove non-default options in REPL commands, Fix help command grouping (#3667)
- Advertise
generate fieldcommand. - Fix #3664. Make config:set --value_format=yaml work. (#3666)
- Allow multipart aliases with drush sa, e.g. @location.site.env or @location.site, in addition to just @location or @site. (#3660)
- Validate any provided config dirs in si command (#3659)
- Do not pass local paths to remote hosts (#3658)
- Automatically select correct profile when using --existing-config (#3657)
- Fix #3634. updatedb with long-running updates can end in "MySQL went away" error (#3655)
- Fix #3624. Change usage of '--config-dir' site-install option. (#3625)
- Fixes #3651: correct typos in topic file paths.
- Fixes #3274: Allow un-found aliases on the commandline to be passed through to the site-local Drush. (#3650)
- Add an 'ssh.tty' option to site aliased. (#3648)
- Fix #3641. Move path doc to non-optional step.
- Fix #3635. More verbose output when an exception happens during command execution. (#3640)
- Set maintenance mode constant running updatedb (#3606)
- Add drush cache directory to core:status (#3623)
- Fix #3596. Canonicalize directory. (#3600)
- Improve site alias example documentation. (#3612)
- Site alias location filters (#3602)
- Enable configurability of the Drush cache directory. (#3597)
- Fix si breaking with uri and default directory (#3591)
- Factor SiteAlias classes out into consolidation/site-alias project. (#3588)
- Fixes #3510: Fix up regular expressions for remote site specifications. (#3583)
- Support ansi options. (#3579)
- Support var-dumper 4.x (#3578)
- Mark drush_backend_invoke_concurrent as deprecated (#3573)
- Fix #3569. Drush 9 aliases path is wrong when using symlink (#3570)
- Fix #3566 - Improve docs for authoring global commandfiles.
- Fix pm:security to properly identify security updates.
The refactoring of the site alias classes into consolidation/site-alias may require minor changes to Drush extensions that reference site alias classes directly (e.g. namespaces will need to be updated).