duplicate ports and the PortIndex

[Dan Ports]

We've had a few duplicate ports recently, usually as part of unifying
Python ports. That's easily fixable -- but, to my surprise, it isn't
enough just to remove one of the offending ports. We also need to make
some change to the remaining port (say, a whitespace change) to force
portindex to re-index it.

If we don't do this, the portindex may still have a reference to the
portfile for the duplicate port that's been deleted. That means that
attempts to open the port -- even just to `port clean all` -- will
fail. (e.g. #32966)

Dan

-- 
Dan R. K. Ports              MIT CSAIL                http://drkp.net/