Count column with name 'count' returns multiple rows. Why?

Hi all,

I don't understand why this query:

select count(base.*) from mytable base;

does return multiple rows.

select count(1) from mytable base;

returns the proper count.

There is a column with the name 'count'.

Can anyone please explain this behaviour?

Steps to reproduce:

create table s91("count" int);
insert into s91 values (1),(2),(3);
select count(base.*) from s91 base;

count
-------
1
2
3
(3 rows)

I think this is either a bug or an undocumented feature?

ps. I posted this question on StackOverflow as well:
https://stackoverflow.com/q/45752412/461499