Drop support for Drupal 6 in next version of Drush

[weitzman]

The next version of Drush will likely support Drupal 7 and 8. Thats a tricky task. I propose we drop Drupal 6 in order to make this a bit more manageable. Drupal 6 users can continue to use Drush 6 ad infinitum.

Feedback?

[greg-1-anderson]

I'm not really in favor of this. If we do #88, I think that it wouldn't be too difficult to have different command classes for each version of Drupal. I'd rather continue D6 support until it's viable to migrate a D7 or D6 site to D8 -- in terms of D8 being final, the migration path being working, and enough contrib being available.

I'll relent if it really becomes impossible, but I'd prefer to refactor a bit and try.

[helmo]

-1 for me. If Import API (https://drupal.org/node/1052692#comment-7903365) plays out well we can migrate from D6 to D8... So I imagine many mixed environments (6,7,8) while this is going on.

[weitzman]

I guess the core motivation here is that we are having trouble keeping up with all the changes in Drupal 8. We need help now. If the maintainers can't get significant help, I'm gonna have to start scoping down Drush 7 and dropping D6 support is a candidate.

[greg-1-anderson]

I'd like to work on D8, but unfortunately I simply don't have the time. It would be my preference to keep Drush master compatible with D6 through D8, but I suppose if you decide not to do that, then I will just stop using the master branch, and will check out and use Drush 6.x everywhere instead.

If this happens, you could also make me the 6.x branch maintainer. This would be an increased efficiency for the project, although a regrettable loss of flexibility for the project. Maybe there aren't a lot of people who care about both D8 and D6 at the same time. Shrug.

If #88 is committed to master, perhaps we could then make a Drush 7.x release at that time, and make Drush 7.x for Drupal 6 and 7, and Drush 8.x (master) for Drupal 7 and 8. (Side effect: nice short-term alignment of version numbers.) This would make it easier to backport from master to the branch that supports Drupal 6.

[weitzman]

Not doing this for now.