bytecomp.el fix for bug#8647

* lisp/emacs-lisp/bytecomp.el (byte-compile-file-form-defmumble):
Let byte-compile-initial-macro-environment always take precedence.

lisp/ChangeLog

+2011-05-12  Glenn Morris  <rgm@gnu.org>
+
+	* emacs-lisp/bytecomp.el (byte-compile-file-form-defmumble):
+	Let byte-compile-initial-macro-environment always take precedence.
+
 2011-05-12  Stefan Monnier  <monnier@iro.umontreal.ca>
 
 	* net/rcirc.el: Add support for SSL/TLS connections.

lisp/emacs-lisp/bytecomp.el

@@ -2421,7 +2421,11 @@ by side-effects."
 
     (let* ((code (byte-compile-lambda (nthcdr 2 form) t)))
       (if this-one
-	  (setcdr this-one code)
+	  ;; A definition in b-c-initial-m-e should always take precedence
+	  ;; during compilation, so don't let it be redefined.  (Bug#8647)
+	  (or (and macrop
+		   (assq name byte-compile-initial-macro-environment))
+	      (setcdr this-one code))
 	(set this-kind
 	     (cons (cons name code)
 		   (symbol-value this-kind))))