[Seaside] A recurring DNU

[Avi Bryant]

Nevin, I can't seem to reproduce this bug.  Can you try adding a fixTemps
to the inner block in #bookmarkForExpiry and see if that helps?  That is,
you want:

>    bookmarkForExpiry
>        ^ Continuation
>            currentDo: [:cc | expiryContinuation _ self
>                            wrapContinuation: [:v |
>                                self redirectWithMessage: 'That page has expired.' delay: 3.
>                                cc value: v] fixTemps]
                                              ^^^^^^^^
Cheers,
Avi