BUG #16462: Update Statement destructive behaviour with joins

The following bug has been logged on the website:

Bug reference:      16462
Logged by:          Aditya Srivastava
Email address:      srivastava.adi24@gmail.com
PostgreSQL version: 9.6.2
Operating system:   MAC OSX
Description:

Let's say I have a table orange and a temp table temp, and i want to update
the records after joining the columns in temp table. I used the following
syntax to update the records which ended up updating the entire table
"orange".

       UPDATE orange
           SET fruit_flag = 'okay'
            FROM temp as t
                   INNER JOIN portal_users p on t.fruit_id = p.fruit_id 
            WHERE p.id = '123';

I know that the correct syntax should be the following but judging from the
destructive nature of this query i honestly feel we should throw validation
error if the above syntax is not correct.


UPDATE orange
SET fruit_flag = 'okay'
FROM temp t
WHERE t.fruit_id = orange.fruit_id 

Thanks in advance.