> - - Start emacs with -Q
> - - Press <f3> and immediately <f4>
> 
> Result (in echo area):
> Only one keyboard macro defined.
> 
> Huh? In fact, there are only *zero* keyboard macros defined (if you do
> not count the empty one that has been ignored).
> 
> Expected result:
> Ignore empty macro

Michael, could you please test the attached patch?  Could you also
test whether it has unwanted side-effects?  Thanks.