bug#31243: 26.1; kmacro-insert-counter increments incorrectly

[Phil Sainty]

Not a bug?  I believe your expectations are incorrect.

> C-u <f3> ;; kmacro-start-macro-or-insert-counter

This insert the *previous* macro counter.  Which is sort of "undefined" 
for the first iteration, but zero in practice.

=> 0

> <f3> ;; kmacro-start-macro-or-insert-counter

Insert the current macro counter (which is also zero, because inserting 
the previous counter does not touch the current counter).

=> 0

Then the counter is incremented -- so the current counter is set to 1, 
and the previous counter is set to 0.

Hence when you trigger the next iteration, you insert 0 and 1; etc...