Aegir (almost) self-upgradeable and possible 6.x support for the next 0.2 release

I have been able to upgrade Aegir with the provision module (that is, manually, on the commandline), but not with Aegir (that is, the hosting frontend) itself directly, because it's much trickier. Nevertheless, the problems impeding manual migration of the base Aegir platform are now behind us, which allows us to easily upgrade (say) the Drupal core behind the frontend. I have documented how in the UPGRADE.txt file.

This brings me to announce some of the IRC discussions we are having right now. We are seriously considering doing a release of 0.2 that will support both Drupal 5 and 6. The original plan was to start working on porting the hosting frontend to Drupal 6 as soon as 0.2 was out, but that would have benefited people only once 0.3 was released, which can be pretty far away. Besides, it would have made the 0.2 to 0.3 upgrade much more difficult. We have also people that manifested themselves on the IRC channel wanting to run Ubercart with Aegir on Drupal 6 and that were ready to work on porting the frontend.

So the approach we will probably be taking now will be to first release 0.2 as planned, but then split it into a DRUPAL-5 branch (for historical purposes and for eventual point releases) then patch HEAD to support Drupal 6, do a last release candidate and then release 6.x-0.2 in full. So you will be able to use provision migrate to upgrade your hostmaster install from Drupal 5 to Drupal 6.

Oh, and we're heading for a beta or release candidate within the next very few days, so this should be coming pretty soon.