ports tree lock

[Peter Valchev <pvalchev@sightly.net>]

A tree lock is now in progress, for version numbers especially.  Nothing
goes in unless there is a good reason for it (an important fix for
something, or along those lines).  In about a week, there will be a
complete lock after which even if something is discovered to be broken,
it stays broken.  This is the way it's going to be this time, play
carefully.