Correctly remove scapy hosts in SRRouting

Change-Id: Iecf55a30cfc341579f1905d80cb15c33bdc10e30
diff --git a/TestON/tests/USECASE/SegmentRouting/dependencies/Testcaselib.py b/TestON/tests/USECASE/SegmentRouting/dependencies/Testcaselib.py
index 7ec46f2..243ff39 100644
--- a/TestON/tests/USECASE/SegmentRouting/dependencies/Testcaselib.py
+++ b/TestON/tests/USECASE/SegmentRouting/dependencies/Testcaselib.py
@@ -1149,7 +1149,8 @@
             main.scapyNames = scapyNames
         else:
             main.scapyNames = main.params[ 'SCAPY' ][ 'HOSTNAMES' ].split( ',' )
-        main.scapyHosts = []
+        if not hasattr( main, "scapyHosts" ):
+            main.scapyHosts = []
         for scapyName in main.scapyNames:
             main.Scapy.createHostComponent( scapyName )
             scapyHandle = getattr( main, scapyName )