Interned pathnames propagating bad information

[David L. Andre <DLA at SCRC-TENEX>]

    BUG-ZWEI at SCRC-TENEX, DLA at SCRC-TENEX

I don't like any of these proposals for Set Package changing the mode
line.  I would have been screwed many times by having that behavior.
Instead, why don't we have the following:

Set * (where * is Package, Base, etc.) will NOT update the mode line.
However, it will print a warning that the package is now different from
that in the mode line, and if you really want things to stay this way
you should do M-X Update Mode Line.  This will not screw Moon and me,
and will help naive users to understand what is happening.

A possible extention is that numeric args to Set * will change the mode
line.  To that I would be agreeable.  But please don't make it a
default.