simple installation of old port versions (was: Lion Recovery Partition)

[Jeremy Lavergne]

> A fairly obvious enhancement that is enabled by having binaries on a
> server is, when the user types 'port install foo @bar', attempting to
> download version bar. (The error reporting needed for this feature alone
> would actually fix #24520.)

That would require validating requested variants be done using the
Portfile from within the archive.

> All the usual gotchas of installing an older binary would apply of
> course. Adding version ranges to dependencies would be the fix for most
> of them, and being able to fetch particular versions would allow
> dependencies on old versions to be handled automatically.
>
> This of course opens its own can of worms regarding detecting and
> resolving dependency conflicts. Getting that working well would put us
> in the position of having that new dependency engine that's been talked
> about for so many years.

Are we going to push in the direction of that dependency engine?