branch: b1_6

let AT estimation cool down before doing AT tests.
b=16990
r=nathan

lustre/tests/replay-single.sh

@@ -1425,6 +1425,10 @@ at_start()
         # speed up the timebase so we can check decreasing AT
 	do_facet mds "echo 8 >> $at_history"
 	do_facet ost1 "echo 8 >> $at_history"
+
+	# sleep for a while to cool down, should be > 8s and also allow
+	# at least one ping to be sent. simply use TIMEOUT to be safe.
+	sleep $TIMEOUT
     fi
 }