Wired if-statement in gen_partprune_steps_internal

Hi:

I found the following code in gen_partprune_steps_internal, which
looks the if-statement to be always true since list_length(results) > 1;
I added an Assert(step_ids != NIL) and all the test cases passed.
if the if-statement is always true, shall we remove it to avoid confusion?

gen_partprune_steps_internal(GeneratePruningStepsContext *context,

if (list_length(result) > 1)
{
List *step_ids = NIL;

foreach(lc, result)
{
PartitionPruneStep *step = lfirst(lc);

step_ids = lappend_int(step_ids, step->step_id);
}
Assert(step_ids != NIL);
if (step_ids != NIL) // This should always be true.
{
PartitionPruneStep *step;

step = gen_prune_step_combine(context, step_ids,

PARTPRUNE_COMBINE_INTERSECT);
result = lappend(result, step);
}
}

--
Best Regards
Andy Fan