Fixed bug mdev-10737.

This bug in st_select_lex_node::move_node could result
in invalid select lists in recursive units that could
cause falling into infinite loops when iterating over
selects in such units.

mysql-test/r/cte_recursive.result

@@ -1611,3 +1611,15 @@ EXPLAIN
   }
 }
 drop table t1;
+#
+# MDEV-10737: recursive union with several anchors at the end
+#
+WITH RECURSIVE cte(n) AS
+( SELECT n+1 FROM cte WHERE n < 5 UNION SELECT 1 UNION SELECT 1 )
+SELECT * FROM cte;
+n
+1
+2
+3
+4
+5

mysql-test/t/cte_recursive.test

@@ -1177,3 +1177,10 @@ select  * from t;
 drop table t1;
 
 
+--echo #
+--echo # MDEV-10737: recursive union with several anchors at the end
+--echo #
+
+WITH RECURSIVE cte(n) AS
+  ( SELECT n+1 FROM cte WHERE n < 5 UNION SELECT 1 UNION SELECT 1 )
+SELECT * FROM cte;

sql/sql_lex.h

@@ -551,6 +551,8 @@ class st_select_lex_node {
   {
     if (where_to_move == this)
       return;
+    if (next)
+      next->prev= prev;
     *prev= next;
     *where_to_move->prev= this;
     next= where_to_move;