fixed 2.5 issues with scheduler

gluon/scheduler.py

@@ -951,10 +951,10 @@ class Scheduler(MetaScheduler):
             orderby = ~st.id | ~sr.id
         row = self.db(q).select(
             *fields,
-            orderby=orderby,
-            left=left,
-            limitby=(0, 1)
-        ).first()
+            **dict(orderby=orderby,
+                   left=left,
+                   limitby=(0, 1))
+             ).first()
         if output:
             row.result = row.scheduler_run.result and \
                 loads(row.scheduler_run.result,