list_free() in index_get_partition()

Seems to be missing.

The 2nd patch does some more cleanup - Before, a failed syscache lookup would
ERROR, but I don't think that's supposed to happen.  get_rel_relispartition()
would instead return false, and we won't call get_partition_parent().

commit a8ad949f22b8dd7b23049b0b0704e5be9233e319
Author: Justin Pryzby <pryzbyj@telsasoft.com>
Date:   Thu Nov 5 12:06:49 2020 -0600

    list_free() in index_get_partition()
    
    which was added at: a6da0047158b8a227f883aeed19eb7fcfbef11fb

diff --git a/src/backend/catalog/partition.c b/src/backend/catalog/partition.c
index 239ac017fa..4dfac39adf 100644
--- a/src/backend/catalog/partition.c
+++ b/src/backend/catalog/partition.c
@@ -153,44 +153,45 @@ Oid
 index_get_partition(Relation partition, Oid indexId)
 {
 	List	   *idxlist = RelationGetIndexList(partition);
 	ListCell   *l;
 
 	foreach(l, idxlist)
 	{
 		Oid			partIdx = lfirst_oid(l);
 		HeapTuple	tup;
 		Form_pg_class classForm;
 		bool		ispartition;
 
 		tup = SearchSysCache1(RELOID, ObjectIdGetDatum(partIdx));
 		if (!HeapTupleIsValid(tup))
 			elog(ERROR, "cache lookup failed for relation %u", partIdx);
 		classForm = (Form_pg_class) GETSTRUCT(tup);
 		ispartition = classForm->relispartition;
 		ReleaseSysCache(tup);
 		if (!ispartition)
 			continue;
-		if (get_partition_parent(lfirst_oid(l)) == indexId)
+		if (get_partition_parent(partIdx) == indexId)
 		{
 			list_free(idxlist);
 			return partIdx;
 		}
 	}
 
+	list_free(idxlist);
 	return InvalidOid;
 }

commit 0a01cb7561d6ec74aa5829040bd1478e7b113d89
Author: Justin Pryzby <pryzbyj@telsasoft.com>
Date:   Thu Nov 5 12:14:24 2020 -0600

    index_get_partition(): use lsyscache ??
    
    The old code failed when !HeapTupleIsValid(), the new code will return false -
    is that ok ??  Two of the existing callers error anyway.

diff --git a/src/backend/catalog/partition.c b/src/backend/catalog/partition.c
index 4dfac39adf..3d78bc0872 100644
--- a/src/backend/catalog/partition.c
+++ b/src/backend/catalog/partition.c
@@ -28,6 +28,7 @@
 #include "partitioning/partbounds.h"
 #include "rewrite/rewriteManip.h"
 #include "utils/fmgroids.h"
+#include "utils/lsyscache.h"
 #include "utils/partcache.h"
 #include "utils/rel.h"
 #include "utils/syscache.h"
@@ -158,17 +159,8 @@ index_get_partition(Relation partition, Oid indexId)
 	foreach(l, idxlist)
 	{
 		Oid			partIdx = lfirst_oid(l);
-		HeapTuple	tup;
-		Form_pg_class classForm;
-		bool		ispartition;
-
-		tup = SearchSysCache1(RELOID, ObjectIdGetDatum(partIdx));
-		if (!HeapTupleIsValid(tup))
-			elog(ERROR, "cache lookup failed for relation %u", partIdx);
-		classForm = (Form_pg_class) GETSTRUCT(tup);
-		ispartition = classForm->relispartition;
-		ReleaseSysCache(tup);
-		if (!ispartition)
+
+		if (!get_rel_relispartition(partIdx))
 			continue;
 		if (get_partition_parent(partIdx) == indexId)
 		{