cycle-real-buffers was a tidbit of complexity that was never necessary
in the first place. This functionality was already available in the form
of the frame buffer-predicate parameter, which controls where functions
like next-buffer and other-buffer can land you.
The only thing I have to do myself, is check for the condition where
there are no more real buffers left to switch to, and in that case send
you to the fallback-buffer.
d1953e00c4