Portupgrade Operation

[Chris Maness]

If I manually rm -rf a port, manually untar (ie glib.tar.gz), and do a 
portupgrade -rR glib, will packages that have a specific dependency on 
the old glib version get rebuilt?  Or if not will they break (I am just 
using glib as an example and looking for a very general answer)?  I 
would like to figure out how portupgrade works without CVSUPing the 
whole port tree.  Like in the case of  a security problem on a 
production server.  I don't necessarily want to rebuild every port that 
has been installed on the box.  Doing this has worked so-far, but I want 
to make sure that this is the best approach, so that I don't end up 
having the mess I had a while back with dependencies.