#14814: Use correct comparison for IP addresses

ipaddress._BaseV4.is_unspecified() compared IP addresses using "in" which
fails.
diff --git a/Lib/ipaddress.py b/Lib/ipaddress.py
index a8edcd1..25bcccd 100644
--- a/Lib/ipaddress.py
+++ b/Lib/ipaddress.py
@@ -1130,7 +1130,7 @@
         """
         unspecified_address = IPv4Address('0.0.0.0')
         if isinstance(self, _BaseAddress):
-            return self in unspecified_address
+            return self == unspecified_address
         return (self.network_address == self.broadcast_address ==
                 unspecified_address)