2 files changed, 18 insertions, 5 deletions

diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 799024ae422..a9cb5a519d0 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,7 @@
+2012-03-26  Ami Fischman  <ami@fischman.org>
+
+        * vc/vc-git.el (vc-git-state): Avoid unnecessarily locking.
+
 2012-03-26  Glenn Morris  <rgm@gnu.org>
 
         * files.el (save-buffers-kill-emacs): Doc fix.
diff --git a/lisp/vc/vc-git.el b/lisp/vc/vc-git.el
index 3ec32243796..bf7b7fb9e17 100644
--- a/lisp/vc/vc-git.el
+++ b/lisp/vc/vc-git.el
@@ -217,12 +217,21 @@ matching the resulting Git log output, and KEYWORDS is a list of
   ;; operation.
   (if (not (vc-git-registered file))
       'unregistered
-    (vc-git--call nil "add" "--refresh" "--" (file-relative-name file))
     (let ((diff (vc-git--run-command-string
-                 file "diff-index" "-z" "HEAD" "--")))
-      (if (and diff (string-match ":[0-7]\\{6\\} [0-7]\\{6\\} [0-9a-f]\\{40\\} [0-9a-f]\\{40\\} \\([ADMUT]\\)\0[^\0]+\0"
-                                  diff))
-          (vc-git--state-code (match-string 1 diff))
+                 file "diff-index" "-p" "--raw" "-z" "HEAD" "--")))
+      (if (and diff
+               (string-match ":[0-7]\\{6\\} [0-7]\\{6\\} [0-9a-f]\\{40\\} [0-9a-f]\\{40\\} \\([ADMUT]\\)\0[^\0]+\0\\(\\(?:.\\|\n\\)*\\)\\'"
+                             diff))
+          (let ((diff-letter (match-string 1 diff))
+                (diff-contents (match-string 2 diff)))
+            (if (not (string-match "\n." diff-contents))
+                ;; Empty diff: file contents is the same as the HEAD
+                ;; revision, but timestamps are different (eg, file
+                ;; was "touch"ed).  Update timestamp in index:
+                (prog1 'up-to-date
+                  (vc-git--call nil "add" "--refresh" "--"
+                                (file-relative-name file)))
+              (vc-git--state-code diff-letter)))
         (if (vc-git--empty-db-p) 'added 'up-to-date)))))
 
 (defun vc-git-working-revision (file)