Fix for bug#38821: Assert table->auto_increment_field_not_null failed

in open_table()

Problem: repeating "CREATE... ( AUTOINCREMENT) ... SELECT" may lead to
an assertion failure.

Fix: reset table->auto_increment_field_not_null after each record 
writing.

mysql-test/r/create.result

@@ -1546,4 +1546,15 @@ SHOW INDEX FROM t1;
 Table	Non_unique	Key_name	Seq_in_index	Column_name	Collation	Cardinality	Sub_part	Packed	Null	Index_type	Comment
 t1	1	c1	1	c1	A	NULL	NULL	NULL	YES	BTREE	
 DROP TABLE t1;
+CREATE TABLE t1 (a INTEGER AUTO_INCREMENT PRIMARY KEY, b INTEGER NOT NULL);
+INSERT IGNORE INTO t1 (b) VALUES (5);
+CREATE TABLE IF NOT EXISTS t2 (a INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY)
+SELECT a FROM t1;
+CREATE TABLE IF NOT EXISTS t2 (a INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY)
+SELECT a FROM t1;
+ERROR 23000: Duplicate entry '1' for key 1
+CREATE TABLE IF NOT EXISTS t2 (a INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY)
+SELECT a FROM t1;
+ERROR 23000: Duplicate entry '1' for key 1
+DROP TABLE t1, t2;
 End of 5.0 tests

mysql-test/t/create.test

@@ -1172,4 +1172,22 @@ SHOW INDEX FROM t1;
 DROP TABLE t1;
 
 
+#
+# Bug#38821: Assert table->auto_increment_field_not_null failed in open_table()
+#
+CREATE TABLE t1 (a INTEGER AUTO_INCREMENT PRIMARY KEY, b INTEGER NOT NULL);
+INSERT IGNORE INTO t1 (b) VALUES (5);
+
+CREATE TABLE IF NOT EXISTS t2 (a INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY)
+  SELECT a FROM t1;
+--error 1062
+CREATE TABLE IF NOT EXISTS t2 (a INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY)
+  SELECT a FROM t1;
+--error 1062
+CREATE TABLE IF NOT EXISTS t2 (a INTEGER NOT NULL AUTO_INCREMENT PRIMARY KEY)
+  SELECT a FROM t1;
+
+DROP TABLE t1, t2;
+
+
 --echo End of 5.0 tests

sql/sql_insert.cc

@@ -2897,7 +2897,11 @@ bool select_insert::send_data(List<Item> &values)
       DBUG_RETURN(1);
     }
   }
-  if (!(error= write_record(thd, table, &info)))
+  
+  error= write_record(thd, table, &info);
+  table->auto_increment_field_not_null= FALSE;
+  
+  if (!error)
   {
     if (table->triggers || info.handle_duplicates == DUP_UPDATE)
     {