PUSH on macroexpanded forms

[REES at MIT-MC (Jonathan A. Rees)]

  There WAS a bug before I recompiled the source for SETF.  
  [Attention Maclisp/NILCOM maintainers (who are you?  The files's
author was Jonl, but I know that he is working on other things): test
out changes you make to the Lisp source files when you make them,
otherwise someone else (like me) has to go and debug your errors, or
suffer confusion when the source doesn't reflect the current state of
the FASL (esp.  when you delete the source that the installed FASL was
created from).  I had both these problems in this instance.