Fix wrong WARNING when own ip is unknown at startup

re6st/cache.py

@@ -203,12 +203,15 @@ class Cache(object):
     def my_address(self):
         for x, in self._db.execute("SELECT address FROM peer WHERE NOT prefix"):
             return x
-        return ''
 
     @my_address.setter
-    def my_address(self, *args):
+    def my_address(self, value):
+        if value:
             with self._db as db:
-            db.execute("INSERT OR REPLACE INTO peer VALUES ('', ?)", args)
+                db.execute("INSERT OR REPLACE INTO peer VALUES ('', ?)",
+                           (value,))
+        else:
+            del self.my_address
 
     @my_address.deleter
     def my_address(self):

re6st/tunnel.py

@@ -213,7 +213,9 @@ class BaseTunnelManager(object):
         if any(address_dict.itervalues()):
             del cache.my_address
         else:
-            for address in utils.parse_address(cache.my_address):
+            address = cache.my_address
+            if address:
+                for address in utils.parse_address(address):
                     try:
                         proto = proto_dict[address[2]]
                     except KeyError: