Confusing title I know, but what I noticed is that the Warehouse level 2 doesn't expand your basic inventory to 50 spaces, but instead adds 50 more spaces.

So I now have 90 spaces (or so my inventory claims), which seems so much I can probably fit anything in there and have no need to expand further. xD

PS: The 10 additional spaces came from a scroll.

I m assuming its just a description fault, mine worked the same, so I submitted it into typo section :3

Edit: oh, nvmd, it reverted to 50 after all XD