migration handling

[Jeremy Lavergne]

> Absolutely, I wouldn't want this to involve piping at all. Couldn't it
> just be stored within the MacPorts prefix? If it needs to be written
> out at all that is; if 'selfupdate' is enough to carry an installation
> across an OS upgrade (I could have sworn this was enough), couldn't
> that data just be held in memory? Or referenced from the existing
> databases? Things could even be further restricted to only supporting
> an /opt/local prefix if that makes things easier if a file is
> required.

I think we suggest uninstall rather than deactivate, so that removes everything from sqlite db; it won't know about those ports' requested status any longer. However, we could make a temporary table that lists the requested-after-migration ports to reinstall.