I'd like to apply this patch. When I use vc-dir, I almost always want to
look at the root of the repository, not the portion that contains the
file I'm editing. What do you think?

diff --git a/lisp/vc/vc-dir.el b/lisp/vc/vc-dir.el
index 8bba79c..e050c94 100644
--- a/lisp/vc/vc-dir.el
+++ b/lisp/vc/vc-dir.el
@@ -1241,7 +1241,7 @@ These are the commands available for use in the
file status buffer:
     ;; Otherwise if you do C-x v d -> C-x C-f -> C-c v d
     ;; you may get a new *vc-dir* buffer, different from the original
     (file-truename (read-directory-name "VC status for directory: "
-					default-directory default-directory t
+					(vc-root-dir) nil t
 					nil))
     (if current-prefix-arg
 	(intern