`WP_Query` allows random ordering; `'orderby' => 'rand'` translates to
`ORDER BY RAND()`. This syntax results in random ordering that is not
consistent from request to request. MySQL supports the passing of a seed value
to random sorts, such as `ORDER BY RAND(3)`, which will return the same
random value each time it's called. `WP_Query` now supports this syntax, by
passing `RAND(3)` (or whatever integer seed value you'd like) as the value
of `'orderby'`.
Props hlashbrooke.
Fixes#35692.
git-svn-id: https://develop.svn.wordpress.org/trunk@36632 602fd350-edb4-49c9-b593-d223f7449a82
0338c8b3a3