Fix setting None for config value

deluge/config.py

@@ -113,9 +113,12 @@ class Config:
     def set(self, key, value):
         """Set the 'key' with 'value'."""
 	    # Sets the "key" with "value" in the config dict
-        if self.config[key] != value:
+        if self.config[key] == value:
+            return
+            
         oldtype, newtype = type(self.config[key]), type(value)
-	    if oldtype != newtype:
+
+        if value is not None and oldtype != newtype:
             try:
                 value = oldtype(value)
             except ValueError: