Refs #16234: Avoid GenericIPAddressField clobbering Field default_error_messages dict.

git-svn-id: http://code.djangoproject.com/svn/django/trunk@16390 bcc190cf-cafb-0310-a4f2-bffc1f526a37

django/db/models/fields/__init__.py

@@ -937,6 +937,7 @@ class IPAddressField(Field):
 class GenericIPAddressField(Field):
     empty_strings_allowed = True
     description = _("IP address")
+    default_error_messages = {}
 
     def __init__(self, protocol='both', unpack_ipv4=False, *args, **kwargs):
         self.unpack_ipv4 = unpack_ipv4