switch-to-buffer-other-window creates a new frame for *scratch* when pop-up-frames is nil

[Greg A. Woods]

In GNU Emacs 21.2.1 (i386--netbsdelf, X toolkit)
 of 2002-10-04 on proven
configured using `configure  --with-x --with-x-toolkit=athena --with-xpm 
--with-jpeg --with-tiff --with-gif --with-png --enable-shared --enable-static 
--host=i386--netbsdelf --prefix=/usr/pkg --x-libraries=/usr/X11R6/lib 
--x-includes=/usr/X11R6/include'
Important settings:
  value of $LC_ALL: nil
  value of $LC_COLLATE: nil
  value of $LC_CTYPE: nil
  value of $LC_MESSAGES: nil
  value of $LC_MONETARY: nil
  value of $LC_NUMERIC: nil
  value of $LC_TIME: nil
  value of $LANG: nil
  locale-coding-system: nil
  default-enable-multibyte-characters: t

Please describe exactly what actions triggered the bug
and the precise symptoms of the bug:

When pressing `o' in the *Buffer List* buffer with the cursor on the
entry for *scratch*, another frame is created instead of another window,
even when pop-up-frames is nil.  This does not happen for any other
buffer.