rewrite bug#26704 test case

drop-no_root needs DROP DATABASE to fail.
But `chmod 000` is not reliable after drop table force anymore.

Make DROP DATABASE to fail by creating an extra file in the db dir

Author: vuvova

mysql-test/main/drop-no_root.result

@@ -131,6 +131,19 @@ create table mysql_test.`#sql-347f_7` (f1 int);
 create table mysql_test.`#sql-347f_8` (f1 int);
 drop table mysql_test.`#sql-347f_8`;
 drop database mysql_test;
+create database mysql_test;
+use mysql_test;
+create table t1(c int);
+drop database mysql_test;
+ERROR HY000: Error dropping database (can't rmdir './mysql_test', errno: 39 "Directory not empty")
+select database();
+database()
+mysql_test
+drop database mysql_test;
+select database();
+database()
+NULL
+use test;
 
 # --
 # -- Bug#29958: Weird message on DROP DATABASE if mysql.proc does not

mysql-test/main/drop-no_root.test

@@ -175,6 +175,27 @@ let $MYSQLD_DATADIR= `select @@datadir`;
 copy_file $MYSQLD_DATADIR/mysql_test/t1.frm $MYSQLD_DATADIR/mysql_test/#sql-347f_6.frm;
 drop database mysql_test;
 
+#
+# Bug#26704: Failing DROP DATABASE brings mysql-client out of sync.
+#
+
+create database mysql_test;
+use mysql_test;
+create table t1(c int);
+
+write_file $MYSQLD_DATADIR/mysql_test/do_not_delete;
+do_not_delete
+EOF
+
+replace_result $MYSQLD_DATADIR ./ \\ / 41 39;
+error ER_DB_DROP_RMDIR;
+drop database mysql_test;
+select database();
+remove_file $MYSQLD_DATADIR/mysql_test/do_not_delete;
+drop database mysql_test;
+select database();
+use test;
+
 ###########################################################################
 
 --echo