src/Pure/General/sql.scala

       var trace_nl = false
 
       def trace(msg: String): Unit = {
         val trace_time = Time.now() - trace_start
         if (trace_time >= trace_min) {
-          val nl = if (trace_nl) "" else { trace_nl = true; "\nnow = " + (Time.now() - time_start).toString + "\n" }
+          time_start
+          val nl =
+            if (trace_nl) ""
+            else { trace_nl = true; "\nnow = " + (Time.now() - time_start).toString + "\n" }
           log(nl + trace_time + " transaction " + trace_count +
             if_proper(label, " " + label) + ": " + msg)
         }
       }