r12389 changes a piece of logic, no?

[Denis-de-Bernardy]

should r12389 read something like:

if ( isset($user_id) && $user_id ) {

?

$user_id if set should always be a positive integer in order for it to make any sense.

It is true that now if $user_id was set to 0 - which has no sensible meaning we will now run the db query and create a WP_User for 0 which we wouldn't have done before.

I will add the second check in to remove this possibility

(In [12391]) Restore the check for trueness on $user_id so we don't run the queries or create the objects. Fixes #11419 props Denis-de-Bernardy.