FYI, I just committed this code to NetBSD-current's pkg_add:

Add -u switch to pkg_add to do a very rudimentare form of pkg upgrading:
When invoked with 'pkg_add -u ...', and the package to be installed is
found already being installed, the old (installed) package is removed
with pkg_delete, and the new one is installed.

A very crude handling of dependencies is done (by moving the +REQUIRED_BY
file aside before pkg_delete, and back into place after the new pkg is
installed).

I'd appreciate testing and any feedback!


 -  Hubert