migration handling

[Jeremy Lavergne]

> No, I get that all ports need to be uninstalled, cleaned, and
> reintalled. I'm talking about reinstalling MacPorts itself. Is it
> necessary to reinstall the MacPorts base software after an OS upgrade?
> I didn't think this was necessary, but the Migration guide says that
> it is. If this isn't so, the guide should be updated, but it also
> simplifies automated migration.

Ah, my bad.

Hmm, well that all depends if system things changed out from under MacPorts. For example, if libcurl breaks:
$ otool -L /opt/local/share/macports/Tcl/pextlib1.0/Pextlib.dylib /opt/local/share/macports/Tcl/pextlib1.0/Pextlib.dylib:
	Pextlib.dylib (compatibility version 0.0.0, current version 0.0.0)
	/usr/lib/libcurl.4.dylib (compatibility version 6.0.0, current version 6.1.0)
	/usr/lib/libedit.2.dylib (compatibility version 2.0.0, current version 2.11.0)
	/usr/lib/libSystem.B.dylib (compatibility version 1.0.0, current version 125.2.11)

Since it can (and has) happened in the past, it's better to just always install a fresh version of the MacPorts files.