bug#46908: 28.0.50; Dozens of spurious markers in buffer-undo-list

[martin rudalics]

> I tried it now.  The only thing I can say is that with Emacs 27 it
> usually returns 0 or 1 here while with master it returns 10.  So maybe
> you should try (after verifying what I found out) to trace the recent
> changes in master.

The "it" above is `count-markers-in-buffer-undo-list'.  And with "trace"
I really meant "bisect".  But make sure to check first what I said about
the Emacs 27 behavior - YMMV.

martin