Do not break build on missing curl results (#6516)

system-test/testnet-performance/testnet-automation-json-parser.py

@@ -5,6 +5,7 @@ data=json.load(sys.stdin)
 
 if 'results' in data:
    for result in data['results']:
+      if 'series' in result:
          print result['series'][0]['columns'][1].encode() + ': ' + str(result['series'][0]['values'][0][1])
 else:
    print "No results returned from CURL request"