[plt-scheme] handle-evt can wrap handle-evt

Hi,

It seems that it is legal for a handle-evt to wrap another handle-evt.
Aren't handle-evts supposed to be terminal events, that cannot be further
wrapped?

Case:
> (version)
"369.8"
> (handle-evt (handle-evt always-evt (lambda x #t)) (lambda x #f))
#<evt>
> (sync (handle-evt (handle-evt always-evt (lambda x #t)) (lambda x #f)))
#f
> (wrap-evt (handle-evt always-evt (lambda x #t)) (lambda x #f))
wrap-evt: expects type <non-handle evt> as 1st argument, given: #<evt>;
other arguments were: #<procedure>

PS: bugs.plt-scheme.org seems to be down...

-- vyzo