A test case for bug in record #166 :

select @@not_a_variable closes the connection

mysql-test/r/variables.result

@@ -335,3 +335,8 @@ Table	Op	Msg_type	Msg_text
 test.t1	check	status	OK
 test.t2	check	status	OK
 drop table t1,t2;
+select @@xxxxxxxxxx;
+Unknown system variable 'xxxxxxxxxx'
+select 1;
+1
+1

mysql-test/t/variables.test

@@ -241,3 +241,10 @@ select * from t2 where a=3;
 check table t1,t2;
 drop table t1,t2;
 
+#
+# error conditions
+#
+
+--error 1193
+select @@xxxxxxxxxx;
+select 1;