[mew-int 2839] Selecting deleted buffer

I just got hit by the following error:

Debugger entered--Lisp error: (error "Selecting deleted buffer")
  byte-code("...")
  mew-cache-message("%list.emacs-devel" "1912" nil no-err)
  mew-summary-cache-prefetch()
  byte-code("...")
  mew-summary-display()
  mew-summary-display-down(nil)
  call-interactively(mew-summary-display-down nil nil)

What I did: In the buffer %list.emacs-devel, I marked a number of
messages (using "mr" twice, for two different regexps), then hit "mt"
and started reading the messages. The above happened when I tried to
read one particular message in the list.

I dug around in the source code a little bit, and found that
mew-cache-message calls mew-cache-hit, so I ran
(mew-cache-hit "%list.emacs-devel" "1912)
in the minibuffer (with M-:) and got hit by the same error.
Digging slightly deeper, I ran
(mew-cache-get "%list.emacs-devel" "1912)
and got (("%list.emacs-devel" . "1912") . #<killed buffer>).

Restarting emacs fixed the problem. Still, I am reporting this in case
the incident points to some part of the code that could be made more
robust.

- Harald