oddity building ports with archiving

[Jack Howarth]

   I've noticed an oddity while building local ports
under MacPorts 1.8.0 with the archiving feature enabled.
It appears that if one is modifying the Portfile without
constantly bumping the revision number that the 'clean'
command is insufficient to purge the previous tgz archive
of the package. This means that while 'sudo port build'
works as expected when 'sudo port install' is executed
the tgz is not recreated. Shouldn't 'sudo port clean'
remove the archives associated with the Portfile? Otherwise
when archive is enabled it seems one has to constantly
delete the archive manually between builds. Or am I missing
something here?
         Jack