git-blame.el: show the when, who and what in the minibuffer.

Change the default operation to show 'when (day the commit was made),
who (who made the commit), what (what the commit log was)' in the
minibuffer instead of SHA1 and title of the commit log.

Since the user may prefer other displaying options, it is made as a
user-configurable option.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

contrib/emacs/git-blame.el

@@ -105,6 +105,13 @@ selected element from l."
      (setq ,l (remove e ,l))
      e))
 
+(defvar git-blame-log-oneline-format
+  "format:[%cr] %cn: %s"
+  "*Formatting option used for describing current line in the minibuffer.
+
+This option is used to pass to git log --pretty= command-line option,
+and describe which commit the current line was made.")
+
 (defvar git-blame-dark-colors
   (git-blame-color-scale "0c" "04" "24" "1c" "2c" "34" "14" "3c")
   "*List of colors (format #RGB) to use in a dark environment.
@@ -371,7 +378,8 @@ See also function `git-blame-mode'."
 (defun git-describe-commit (hash)
   (with-temp-buffer
     (call-process "git" nil t nil
-                  "log" "-1" "--pretty=oneline"
+                  "log" "-1"
+		  (concat "--pretty=" git-blame-log-oneline-format)
                   hash)
     (buffer-substring (point-min) (1- (point-max)))))