ob: fix empty-argument bug introduced by recent inline call lines

* lisp/ob-lob.el (org-babel-lob-get-info): If the arguments are empty,
  then allow them to be so.

lisp/ob-lob.el

@@ -112,7 +112,7 @@ if so then run the appropriate source block from the Library."
 			    (nonempty 3 12)
 			    (if (not (= 0 (length (nonempty 5 13))))
 				(concat "[" (nonempty 5 13) "]") "")
-			    (nonempty 7 16)
+			    (or (nonempty 7 16) "")
 			    (or (nonempty 8 18) ""))
 		    (nonempty 9 17)))
 	   (list (length (nonempty 1 11)))))))))