The new (0.9.6.52) shrink-vector should be used for its return value,
as opposed to the old one (now known as %shrink-vector), which was used
for its side effect (but also had a useful return value).
sb-impl::vector-delete-duplicates* hasn't yet been updated to reflect
this. This resulted in three ansi-tests failures (that were reported by
Brian Mastenbrook on #lisp). Attached is a fix for this.
Another problem probably occurs in sb-kernel::compact-environment-aux
(called by purify). The result of shrink-vector doesn't appear to be
used here, so it seems to have no effect anymore. Sorry, no fix for
this one from me.