undo after repeatedly calling 'repeat' leaves cursor in the wrong place

[Chris Moore]

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.