How to get the old "other window" back?

[Bob Rogers]

   I just updated trunk for the first time in three weeks, and find that
C-x 4 b has a new interpretation of "other window"; it keeps popping up
windows in new frames.  The code for this is wondrously obscure; I have
been unable to figure out how to tell it to stick to the current frame.
Does anybody have a recipe that restores the traditional behavior?

   TIA (and apologies for being unwilling to invest the rest of my
sanity on wading through the new implementation),

                                        -- Bob Rogers
                                           http://www.rgrjr.com/