MDEV-38667 Assertion in diagnostics area on DDL stats timeout

Reason:
======
 During InnoDB DDL, statistics updation fails due to lock wait
timeout and calls push_warning_printf() to generate warnings
but then returns success, causing the SQL layer
to attempt calling set_ok_status() when the diagnostics area
is already set.

Solution:
=========
By temporarily setting abort_on_warning to false around operations
that prevents warning to error escalation and restore the original
setting after calling HA_EXTRA_END_ALTER_COPY for alter operation.

Author: Thirunarayanan

mysql-test/suite/innodb/r/alter_copy_stats.result

@@ -103,3 +103,13 @@ n_rows	database_name	lower(table_name)
 # Test Cleanup.
 DROP TABLE t1;
 DROP TABLE t2;
+#
+# MDEV-38667 Assertion in diagnostics area on DDL stats timeout
+#
+set @lock_wait_timeout= @@global.innodb_lock_wait_timeout;
+SET innodb_lock_wait_timeout = 1;
+CREATE TABLE t ENGINE=InnoDB AS SELECT * FROM mysql.innodb_table_stats;
+Warnings:
+Warning	1088	Error updating stats for table after table rebuild: Lock wait timeout
+SET innodb_lock_wait_timeout = @lock_wait_timeout;
+DROP TABLE t;

mysql-test/suite/innodb/t/alter_copy_stats.test

@@ -88,3 +88,12 @@ FROM mysql.innodb_table_stats WHERE table_name LIKE '%t2%';
 --echo # Test Cleanup.
 DROP TABLE t1;
 DROP TABLE t2;
+
+--echo #
+--echo # MDEV-38667 Assertion in diagnostics area on DDL stats timeout
+--echo #
+set @lock_wait_timeout= @@global.innodb_lock_wait_timeout;
+SET innodb_lock_wait_timeout = 1;
+CREATE TABLE t ENGINE=InnoDB AS SELECT * FROM mysql.innodb_table_stats;
+SET innodb_lock_wait_timeout = @lock_wait_timeout;
+DROP TABLE t;

sql/sql_insert.cc

@@ -4382,7 +4382,14 @@ bool select_insert::prepare_eof()
   if (info.ignore || info.handle_duplicates != DUP_ERROR)
       if (table->file->ha_table_flags() & HA_DUPLICATE_POS)
         table->file->ha_rnd_end();
+
+  /* Don't convert the warning to error in case
+  statistics updation fails */
+  bool save_abort_on_warning= thd->abort_on_warning;
+  thd->abort_on_warning= false;
   table->file->extra(HA_EXTRA_END_ALTER_COPY);
+  thd->abort_on_warning= save_abort_on_warning;
+
   table->file->extra(HA_EXTRA_NO_IGNORE_DUP_KEY);
   table->file->extra(HA_EXTRA_WRITE_CANNOT_REPLACE);