MDEV-10424 - Assertion `ticket == __null' failed in MDL_request::set_type

Reexecution of prepared "ANALYZE TABLE merge_table, table" may miss to
reinitialize "table" for subsequent execution and trigger assertion failure.

This happens because MERGE engine may adjust table->next_global chain, which
gets cleared by close_thread_tables()/ha_myisammrg::detach_children() later.
Since reinitilization iterates next_global chain, it won't see tables following
merge table.

Fixed by appending saved next_global chain after merge children.

Author: svoj

mysql-test/r/merge.result

@@ -3832,4 +3832,21 @@ test.m1	repair	error	Corrupt
 # Clean-up.
 drop tables m1, t1, t4;
 drop view t3;
+#
+# MDEV-10424 - Assertion `ticket == __null' failed in
+#              MDL_request::set_type
+#
+CREATE TABLE t1 (f1 INT) ENGINE=MyISAM;
+CREATE TABLE tmerge (f1 INT) ENGINE=MERGE UNION=(t1);
+PREPARE stmt FROM "ANALYZE TABLE tmerge, t1";
+EXECUTE stmt;
+Table	Op	Msg_type	Msg_text
+test.tmerge	analyze	note	The storage engine for the table doesn't support analyze
+test.t1	analyze	status	Table is already up to date
+EXECUTE stmt;
+Table	Op	Msg_type	Msg_text
+test.tmerge	analyze	note	The storage engine for the table doesn't support analyze
+test.t1	analyze	status	Table is already up to date
+DEALLOCATE PREPARE stmt;
+DROP TABLE t1, tmerge;
 End of 5.5 tests

mysql-test/t/merge.test

@@ -2880,6 +2880,19 @@ drop tables m1, t1, t4;
 drop view t3;
 
 
+--echo #
+--echo # MDEV-10424 - Assertion `ticket == __null' failed in
+--echo #              MDL_request::set_type
+--echo #
+CREATE TABLE t1 (f1 INT) ENGINE=MyISAM;
+CREATE TABLE tmerge (f1 INT) ENGINE=MERGE UNION=(t1);
+PREPARE stmt FROM "ANALYZE TABLE tmerge, t1";
+EXECUTE stmt;
+EXECUTE stmt;
+DEALLOCATE PREPARE stmt;
+DROP TABLE t1, tmerge;
+
+
 --echo End of 5.5 tests
 
 --disable_result_log

sql/sql_admin.cc

@@ -441,7 +441,19 @@ static bool mysql_admin_table(THD* thd, TABLE_LIST* tables,
       }
       thd->prepare_derived_at_open= FALSE;
 
-      table->next_global= save_next_global;
+      /*
+        MERGE engine may adjust table->next_global chain, thus we have to
+        append save_next_global after merge children.
+      */
+      if (save_next_global)
+      {
+        TABLE_LIST *table_list_iterator= table;
+        while (table_list_iterator->next_global)
+          table_list_iterator= table_list_iterator->next_global;
+        table_list_iterator->next_global= save_next_global;
+        save_next_global->prev_global= &table_list_iterator->next_global;
+      }
+
       table->next_local= save_next_local;
       thd->open_options&= ~extra_open_options;