Re: postinstall wiped out my /etc/rc changes

[Greg Troxel <gdt%ir.bbn.com@localhost>]

  I think it's more complex than that.  It isn't obvious -- at least not
  to me -- which files in /etc are "owned" by the system (and hence are
  fair game for auto-replacement), and which are owned by the
  administrator.  (I raised similar questions a few months ago about the
  power management scripts.)  We need a clear, clean way to make that
  distinction, and to make it obvious to the community.

See pkgsrc/sysutil/etcmanage.  The rule there is that a file is owned by
the system if it is marked automatically managed and is unmodified from
when it was marked (hash registered in db).  I've been updating many
systems with this for years with no surprises.