Fix reversed IPv4Forwarding check in api.go

api.go

@@ -522,7 +522,7 @@ func postContainersCreate(srv *Server, version float64, w http.ResponseWriter, r
 		out.Warnings = append(out.Warnings, "Your kernel does not support memory swap capabilities. Limitation discarded.")
 	}
 
-	if srv.runtime.capabilities.IPv4Forwarding {
+	if !srv.runtime.capabilities.IPv4Forwarding {
 		log.Println("Warning: IPv4 forwarding is disabled.")
 		out.Warnings = append(out.Warnings, "IPv4 forwarding is disabled.")
 	}