New bindings for vc-revert

* lisp/vc/vc-dir.el (vc-dir-mode-map): Bind vc-revert to '@'.
* lisp/vc/vc-hooks.el (vc-prefix-map): Additionally bind
vc-revert to 'C-x v @'.
* doc/emacs/maintaining.texi (VC Undo, VC Directory Commands):
* etc/NEWS: Document the change.

doc/emacs/maintaining.texi

@@ -1360,6 +1360,7 @@ also prompt for a specific VCS shell command to run for this purpose.
 
 @table @kbd
 @item C-x v u
+@item C-x v @@
 Revert the work file(s) in the current VC fileset to the last revision
 (@code{vc-revert}).
 
@@ -1374,24 +1375,25 @@ Delete an unpushed commit from the revision history.
 @end table
 
 @kindex C-x v u
+@kindex C-x v @@
 @findex vc-revert
 @vindex vc-revert-show-diff
-  If you want to discard all the changes you have made to the current
-VC fileset, type @kbd{C-x v u} (@code{vc-revert}).  This will ask you
-for confirmation before discarding the changes.  If you agree, the
-fileset is reverted.
+  If you want to discard all the changes you have made to the current VC
+fileset, type @kbd{C-x v u} or @kbd{C-x v @@} (@code{vc-revert}).  This
+will ask you for confirmation before discarding the changes.  If you
+agree, the fileset is reverted.
 
   If @code{vc-revert-show-diff} is non-@code{nil}, this command will
-show you a diff between the work file(s) and the revision from which
-you started editing.  Afterwards, the diff buffer will either be
-killed (if this variable is @code{kill}), or the buffer will be buried
-(any other non-@code{nil} value).  If you don't want @kbd{C-x v u} to
-show a diff, set this variable to @code{nil} (you can still view the
-diff directly with @kbd{C-x v =}; @pxref{Old Revisions}).
+show you a diff between the work file(s) and the revision from which you
+started editing.  Afterwards, the diff buffer will either be killed (if
+this variable is @code{kill}), or the buffer will be buried (any other
+non-@code{nil} value).  If you don't want @code{vc-revert} to show you
+diffs, set this variable to @code{nil} (you can still view the diff
+directly with @kbd{C-x v =}; @pxref{Old Revisions}).
 
-  On locking-based version control systems, @kbd{C-x v u} leaves files
-unlocked; you must lock again to resume editing.  You can also use
-@kbd{C-x v u} to unlock a file if you lock it and then decide not to
+  On locking-based version control systems, @code{vc-revert} leaves
+files unlocked; you must lock again to resume editing.  You can also use
+@code{vc-revert} to unlock a file if you lock it and then decide not to
 change it.
 
 @findex vc-revert-or-delete-revision
@@ -1641,6 +1643,10 @@ ignore (@code{vc-dir-ignore}).  For instance, if the VC is Git, it
 will append this file to the @file{.gitignore} file.  If given a
 prefix, do this with all the marked files.
 
+@item @@
+Discard all the changes you have made to the current fileset
+(@code{vc-revert}).
+
 @item q
 Quit the VC Directory buffer, and bury it (@code{quit-window}).
 

etc/NEWS

@@ -2599,8 +2599,15 @@ cloning, or prompts for that, too.
 When the argument is non-nil, the function switches to a buffer visiting
 the directory into which the repository was cloned.
 
++++
+*** 'vc-revert' is now bound to '@' in VC-Dir.
+
++++
+*** 'vc-revert' is now additionally bound to 'C-x v @'.
+This is in addition to 'C-x v u'.
+
 ---
-*** 'C-x v u' ('vc-revert') now works on directories listed in VC Directory.
+*** 'vc-revert' now works on directories listed in VC Directory.
 Reverting a directory means reverting changes to all files inside it.
 
 +++

lisp/vc/vc-dir.el

@@ -396,6 +396,7 @@ That is, refreshing the VC-Dir buffer also hides `up-to-date' and
     (define-key map (kbd "M-s a C-s")   #'vc-dir-isearch)
     (define-key map (kbd "M-s a M-C-s") #'vc-dir-isearch-regexp)
     (define-key map "G" #'vc-dir-ignore)
+    (define-key map "@" #'vc-revert)
 
     (let ((branch-map (make-sparse-keymap)))
       (define-key map "b" branch-map)

lisp/vc/vc-hooks.el

@@ -1023,7 +1023,8 @@ In the latter case, VC mode is deactivated for this buffer."
   "m"   #'vc-merge
   "r"   #'vc-retrieve-tag
   "s"   #'vc-create-tag
-  "u"   #'vc-revert
+  "u"   #'vc-revert                     ; The traditional binding.
+  "@"   #'vc-revert                     ; Following VC-Dir's binding.
   "v"   #'vc-next-action
   "+"   #'vc-update
   "P"   #'vc-push