Fix PAC error in test script.

script/test.sh

@@ -88,4 +88,6 @@ if [[ -z $TRAVIS ]]; then
 fi
 
 stop_cow
+sleep 0.5
+rm -f ./script/stat*
 exit 0

sitestat.go

@@ -426,11 +426,14 @@ var siteStat = newSiteStat()
 func initSiteStat() {
 	err := siteStat.load(config.StatFile)
 	if err != nil {
-		// Simply try to load the stat.back
+		// Simply try to load the stat.back, create a new object to avoid error
+		// in default site list.
+		siteStat = newSiteStat()
 		err = siteStat.load(config.StatFile + ".bak")
 		// After all its not critical , simply re-create a stat object if anything is not ok
 		if err != nil {
 			siteStat = newSiteStat()
+			siteStat.load("") // load default site list
 		}
 	}