Convert interval into seconds

The correct way to convert interval into seconds is to use
"EXTRACT(EPOCH FROM ...)". The "SECOND" gives only the value of the second
field.

issue9126
review297181005

trytond/ir/queue.py

@@ -108,7 +108,7 @@ class Queue(ModelSQL):
             selected.for_ = For('UPDATE')
 
         next_timeout = With('seconds', query=candidates.select(
-                Min(Extract('second',
+                Min(Extract('EPOCH',
                         candidates.scheduled_at - CurrentTimestamp())
                     ),
                 where=candidates.scheduled_at >= CurrentTimestamp()))