WHILE 1=1 in the SQL procedure, so that the loop will actually be
entered and temporary indexes be dropped during crash recovery.
Thanks to Sunny Bains for pointing this out.

Tested as follows:

Set a breakpoint in row_merge_rename_indexes.

CREATE TABLE t(a INT)ENGINE=InnoDB;
CREATE INDEX a ON t(a);

-- The breakpoint will be reached.  Kill and restart mysqld.
SHOW CREATE TABLE t;
-- This shows the MySQL .frm file, without and index.
CREATE TABLE innodb_table_monitor(a INT)ENGINE=InnoDB;
-- This will dump the InnoDB dictionary to the error log, without the index.