Fix crash when ALTER TABLE recreates indexes on partitions

The skip_build flag was not being passed correctly when recursing to
indexes on partitions, leading to attempts to rebuild indexes when they
were not yet ready to be rebuilt.

Reported-by: Rajkumar Raghuwanshi
Discussion: https://postgr.es/m/CAKcux6mxNCGsgATwf5CGMF8g4WSupCXicCVMeKUTuWbyxHOMsQ@mail.gmail.com

src/backend/commands/indexcmds.c

@@ -1033,7 +1033,7 @@ DefineIndex(Oid relationId,
 								indexRelationId,	/* this is our child */
 								createdConstraintId,
 								is_alter_table, check_rights, check_not_in_use,
-								false, quiet);
+								skip_build, quiet);
 				}
 
 				pfree(attmap);

src/test/regress/expected/indexing.out

@@ -40,6 +40,14 @@ SELECT col2 FROM idxpart_two fk LEFT OUTER JOIN idxpart pk ON (col1 = col2);
 (0 rows)
 
 DROP table idxpart, idxpart_two;
+-- Verify bugfix with index rewrite on ALTER TABLE / SET DATA TYPE
+-- https://postgr.es/m/CAKcux6mxNCGsgATwf5CGMF8g4WSupCXicCVMeKUTuWbyxHOMsQ@mail.gmail.com
+CREATE TABLE idxpart (a INT, b TEXT, c INT) PARTITION BY RANGE(a);
+CREATE TABLE idxpart1 PARTITION OF idxpart FOR VALUES FROM (MINVALUE) TO (MAXVALUE);
+CREATE INDEX partidx_abc_idx ON idxpart (a, b, c);
+INSERT INTO idxpart (a, b, c) SELECT i, i, i FROM generate_series(1, 50) i;
+ALTER TABLE idxpart ALTER COLUMN c TYPE numeric;
+DROP TABLE idxpart;
 -- If a table without index is attached as partition to a table with
 -- an index, the index is automatically created
 create table idxpart (a int, b int, c text) partition by range (a);

src/test/regress/sql/indexing.sql

@@ -26,6 +26,15 @@ CREATE TABLE idxpart_two (col2 INT);
 SELECT col2 FROM idxpart_two fk LEFT OUTER JOIN idxpart pk ON (col1 = col2);
 DROP table idxpart, idxpart_two;
 
+-- Verify bugfix with index rewrite on ALTER TABLE / SET DATA TYPE
+-- https://postgr.es/m/CAKcux6mxNCGsgATwf5CGMF8g4WSupCXicCVMeKUTuWbyxHOMsQ@mail.gmail.com
+CREATE TABLE idxpart (a INT, b TEXT, c INT) PARTITION BY RANGE(a);
+CREATE TABLE idxpart1 PARTITION OF idxpart FOR VALUES FROM (MINVALUE) TO (MAXVALUE);
+CREATE INDEX partidx_abc_idx ON idxpart (a, b, c);
+INSERT INTO idxpart (a, b, c) SELECT i, i, i FROM generate_series(1, 50) i;
+ALTER TABLE idxpart ALTER COLUMN c TYPE numeric;
+DROP TABLE idxpart;
+
 -- If a table without index is attached as partition to a table with
 -- an index, the index is automatically created
 create table idxpart (a int, b int, c text) partition by range (a);