> Type
>   "x C-x z z z z C-x u"
> (to insert an 'x', repeat the insert 4 times, then undo the last of the 4)
> 
> Before the "C-x u" there were 5 'x's with the cursor after them all.
> After the "C-x u" there are 4 'x's, as expected, but the cursor is on
> the 2nd one, whereas I would expect it to be after the 4th one.
> 
> If "C-x z" is used in full each time, instead of just hitting 'z' over
> and over, then the undo works as expected.

Could you please try the attached patch - against EMACS_22_BASE - and
tell whether it does the right thing.