Re: tablecmds: reject CLUSTER ON for partitioned tables earlier

> I added two new test cases in 0002 that trigger the check.

I also tested these scenarios previously. It's good that they are part
of the test suite, but they don't hit that error path. Verified with
this:

diff --git a/src/backend/commands/tablecmds.c b/src/backend/commands/tablecmds.c
index 379f4d4ebaf..50f80724cb3 100644
--- a/src/backend/commands/tablecmds.c
+++ b/src/backend/commands/tablecmds.c
@@ -17857,9 +17857,7 @@ ATExecDropInherit(Relation rel, RangeVar
*parent, LOCKMODE lockmode)
  Relation parent_rel;

  if (rel->rd_rel->relispartition)
- ereport(ERROR,
- (errcode(ERRCODE_WRONG_OBJECT_TYPE),
- errmsg("cannot change inheritance of a partition")));
+ Assert(0);

  /*
  * AccessShareLock on the parent is probably enough, seeing that DROP