Tar problem

I don't know how new this is but it didn't occur the last time I tried
to unpack the ports collection (probably a year ago).   I haven't got
room on my usr disk for ports, so I symlink it off to a bulk disk 
(hardware, not nfs).  When I unpack the ports collection, the symlink 
has been overwritten with the real directory (in this case it'll barely 
fit, but no builds work inside it...).

I see that the default tar on this system is still gtar - I don't remember
this behavior from the last time I tried the same thing.

I only mention this because it is a real bother, and I've seen talk about
changing versions of tar...  Does the new version do the same?  and/or
is there an option whose default changed (like --posix?).  If this is posix
behavior then I see it as yet another gratuitous change that posix made
just to bother old users (there are LOTS of those; the arg changes to
sort, for another example).

-- Pete