rollback mysql driver

this https://github.com/go-sql-driver/mysql/pull/302 seems to have pretty much
crippled the ability to use mysql, so we need to lock a version before that
until that issue gets fixed.

vendor/github.com/go-sql-driver/mysql/driver_go18_test.go

@@ -520,41 +520,3 @@ func TestContextBeginIsolationLevel(t *testing.T) {
 		tx2.Commit()
 	})
 }
-
-func TestContextBeginReadOnly(t *testing.T) {
-	runTests(t, dsn, func(dbt *DBTest) {
-		dbt.mustExec("CREATE TABLE test (v INTEGER)")
-		ctx, cancel := context.WithCancel(context.Background())
-		defer cancel()
-
-		tx, err := dbt.db.BeginTx(ctx, &sql.TxOptions{
-			ReadOnly: true,
-		})
-		if _, ok := err.(*MySQLError); ok {
-			dbt.Skip("It seems that your MySQL does not support READ ONLY transactions")
-			return
-		} else if err != nil {
-			dbt.Fatal(err)
-		}
-
-		// INSERT queries fail in a READ ONLY transaction.
-		_, err = tx.ExecContext(ctx, "INSERT INTO test VALUES (1)")
-		if _, ok := err.(*MySQLError); !ok {
-			dbt.Errorf("expected MySQLError, got %v", err)
-		}
-
-		// SELECT queries can be executed.
-		var v int
-		row := tx.QueryRowContext(ctx, "SELECT COUNT(*) FROM test")
-		if err := row.Scan(&v); err != nil {
-			dbt.Fatal(err)
-		}
-		if v != 0 {
-			dbt.Errorf("expected val to be 0, got %d", v)
-		}
-
-		if err := tx.Commit(); err != nil {
-			dbt.Fatal(err)
-		}
-	})
-}