Add trivial test case to make sure shared-cache mode does not automatically turn on exclusive-locking mode.

FossilOrigin-Name: a0ab3902f1431c962a5d034647ef3c6876dc0e75

test/savepoint.test

@@ -1026,6 +1026,7 @@ do_multiclient_test tn {
 # (even though it had been removed from the database by the ROLLBACK 
 # command).
 #
+sqlite3 db test.db
 do_execsql_test savepoint-17.1 {
   BEGIN;
     CREATE TABLE t6(a, b);