The document's description of hash-table-intersection! reads:

  Deletes the associations from hash-table1 which don't also appear in
  hash-table2 and returns hash-table1.

However, the sample implementation does not delete an association from
hash-table-1 if an association with the same key appears in
hash-table-2.

Based on similarity with the other procedures in this section, I would
guess that it is the description, not the implementaion, that needs to
be changed.

Regards,

-chaw