tests: fix race condition in punt tests

Type: fix

Signed-off-by: Dave Wallace <dwallacelf@gmail.com>
Change-Id: I6cb13e044bbb966cbb61802094e96220d3a0c951
diff --git a/test/test_punt.py b/test/test_punt.py
old mode 100644
new mode 100755
index c6d6dbc..bc2196e
--- a/test/test_punt.py
+++ b/test/test_punt.py
@@ -83,6 +83,7 @@
     def close(self):
         self.sock.close()
         self.keep_running = False
+        threading.Thread.join(self)
         return self.rx_pkts
 
 
@@ -131,7 +132,6 @@
         rx_pkts = []
         for thread in self.sock_servers:
             rx_pkts += thread.close()
-            thread.join()
         return rx_pkts
 
     def verify_port(self, pr, vpr):