(set-mark-command): Deactivate mark on second C-SPC C-SPC

when using transient-mark-mode.

etc/NEWS

@@ -136,6 +136,8 @@ the currently selected Emacs frame.
 
 ** Emacs now supports the SVG image format through librsvg2.
 
+** C-SPC C-SPC in transient-mark-mode pushes a mark without activating it.
+
 ** transient-mark-mode is now enabled by default.
 
 ** If you set find-file-confirm-nonexistent-file to t, then C-x C-f

lisp/ChangeLog

+2008-02-26  Stefan Monnier  <monnier@iro.umontreal.ca>
+
+	* simple.el (set-mark-command): Deactivate mark on second C-SPC C-SPC
+	when using transient-mark-mode.
+
 2008-02-26  Jan Dj$(Q)Z(Brv  <jan.h.d@swipnet.se>
 	* progmodes/grep.el (grep-mode-tool-bar-map): Change place on next

lisp/simple.el

@@ -3499,6 +3499,9 @@ purposes.  See the documentation of `set-mark' for more information."
 	 mark-active (null transient-mark-mode))
     (setq transient-mark-mode 'lambda)
     (message "Transient-mark-mode temporarily enabled"))
+   ((and (eq last-command 'set-mark-command)
+         transient-mark-mode)
+    (deactivate-mark))
    (t
     (push-mark-command nil))))
 
@@ -4598,7 +4601,6 @@ The variable `selective-display' has a separate value for each buffer."
   (princ "." t))
 
 (defvaralias 'indicate-unused-lines 'indicate-empty-lines)
-(defvaralias 'default-indicate-unused-lines 'default-indicate-empty-lines)
 
 (defun toggle-truncate-lines (&optional arg)
   "Toggle whether to fold or truncate long lines for the current buffer.