hash table question

[sandra%utah-orion@utah-cs.arpa (Sandra J Loosemore)]

Is hashing supposed to "work" if destructive operations are performed on
the hashed object, or is the hash index computed for an object a function
of what's "in" the object rather than the object itself?  As an example,
does this bit of code always return true?

(let* ((cons  (cons 'a 'b))
       (before  (sxhash cons))
       (after   (sxhash (rplaca cons 'foobar))))
      (eql before after))

-Sandra
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