Fixed listener registry to eject listeners only if they indeed exceed the limit.

Change-Id: Ic9453b5b1eabc3d9c92af01e6817612e710bfba8
diff --git a/tools/test/scenarios/net-link-down-up.xml b/tools/test/scenarios/net-link-down-up.xml
index fda756a..70a8fee 100644
--- a/tools/test/scenarios/net-link-down-up.xml
+++ b/tools/test/scenarios/net-link-down-up.xml
@@ -19,11 +19,11 @@
         <step name="Ping-1"
               exec="onos-mininet sendAndExpect h1 ping -c1 h4 --expect \ 0% packet loss"/>
         <step name="Link-1-Down" requires="Ping-1"
-              exec="onos-mininet sendAndExpect link s4 s5 down --expect ."/>
+              exec="onos-mininet sendAndExpect link s4 s7 down --expect ."/>
         <step name="Ping-2" requires="Link-1-Down"
               exec="onos-mininet sendAndExpect h1 ping -c1 h4 --expect \ 0% packet loss"/>
         <step name="Link-2-Down" requires="Ping-2"
-              exec="onos-mininet sendAndExpect link s4 s7 down --expect ."/>
+              exec="onos-mininet sendAndExpect link s4 s5 down --expect ."/>
         <step name="Ping-3" requires="Link-2-Down"
               exec="onos-mininet sendAndExpect h1 ping -c1 h4 --expect 100% packet loss"/>
         <step name="Link-1-Up" requires="Ping-3"