Fix inherited UPDATE for cases where child column numbering doesn't

match parent table.  This used to work, but was broken in 7.3 by
rearrangement of code that handles targetlist sorting.  Add a regression
test to catch future breakage.

src/test/regress/expected/alter_table.out

@@ -1179,3 +1179,31 @@ order by relname, attnum;
 drop table p1, p2 cascade;
 NOTICE:  Drop cascades to table c1
 NOTICE:  Drop cascades to table gc1
+-- test renumbering of child-table columns in inherited operations
+create table p1 (f1 int);
+create table c1 (f2 text, f3 int) inherits (p1);
+alter table p1 add column a1 int check (a1 > 0);
+alter table p1 add column f2 text;
+NOTICE:  ALTER TABLE: merging definition of column "f2" for child c1
+insert into p1 values (1,2,'abc');
+insert into c1 values(11,'xyz',33,0); -- should fail
+ERROR:  ExecInsert: rejected due to CHECK constraint "p1_a1" on "c1"
+insert into c1 values(11,'xyz',33,22);
+select * from p1;
+ f1 | a1 | f2  
+----+----+-----
+  1 |  2 | abc
+ 11 | 22 | xyz
+(2 rows)
+
+update p1 set a1 = a1 + 1, f2 = upper(f2);
+select * from p1;
+ f1 | a1 | f2  
+----+----+-----
+  1 |  3 | ABC
+ 11 | 23 | XYZ
+(2 rows)
+
+drop table p1 cascade;
+NOTICE:  Drop cascades to table c1
+NOTICE:  Drop cascades to constraint p1_a1 on table c1

src/test/regress/sql/alter_table.sql

@@ -849,3 +849,21 @@ where relname in ('p1','p2','c1','gc1') and attnum > 0 and not attisdropped
 order by relname, attnum;
 
 drop table p1, p2 cascade;
+
+-- test renumbering of child-table columns in inherited operations
+
+create table p1 (f1 int);
+create table c1 (f2 text, f3 int) inherits (p1);
+
+alter table p1 add column a1 int check (a1 > 0);
+alter table p1 add column f2 text;
+
+insert into p1 values (1,2,'abc');
+insert into c1 values(11,'xyz',33,0); -- should fail
+insert into c1 values(11,'xyz',33,22);
+
+select * from p1;
+update p1 set a1 = a1 + 1, f2 = upper(f2);
+select * from p1;
+
+drop table p1 cascade;