Ember sortBy on property:desc is not the same as reverse

In Ember 2, I tried sortBy on an Enumerable.

The sortBy('something:asc') works correct. But sortby('something:desc') is not the same as sortBy('something:asc').reverse(). ( Is it not desc?)

I tried to change something property to boolean or string or number. It seems only "string" type works with reverse.