Use format string for message

TINYCHANGE

lisp/ob-ledger.el

@@ -52,7 +52,7 @@ called by `org-babel-execute-src-block'."
         (in-file (org-babel-temp-file "ledger-"))
 	(out-file (org-babel-temp-file "ledger-output-")))
     (with-temp-file in-file (insert body))
-    (message (concat "ledger"
+    (message "%s" (concat "ledger"
 		     " -f " (org-babel-process-file-name in-file)
 		     " " cmdline))
     (with-output-to-string