injector: use more efficient exists() method

injector

@@ -19,8 +19,9 @@ for line in f:
 	# check for already existed hosts in database to avoid adding duplicates
 	# 1. do lookup by hostname
 	# 2. do lookup by base64 hash
-	if not i2phost.objects.filter(name=entry[0]) \
-			and not i2phost.objects.filter(b64hash=entry[1]):
+	qs1 = i2phost.objects.filter(name=entry[0])
+	qs2 = i2phost.objects.filter(name=entry[1])
+	if not qs1.exists() and not qs2.exists():
 		print 'Adding %s' % entry[0]
 		host = i2phost(name=entry[0], b64hash=entry[1],
 				description='Auto-added from external hosts.txt',