I just updated Carpenter's Blocks in my modpack from 3.3.7 to 3.3.8. When I'm trying to change slope block to shown in the screenshot I can't do that. On 3.3.7 I can.
That is a bug or something? I'm using Carpenter's Hammer. I can only rotate blocks with it :c Block shown on screenshot is placed on old version of mod. New blocks on new version cannot be formed to that form.
Sorry for my bad English ^^"

Yay! I got it! Thank You for advice c:

I've added the functionality back and you will see it in 3.3.8.1. Rotation functionality will be moved to sneak right-click with hammer.

Yeah, that functionality was removed when I added proper rotation support to slopes, and it seemed more convenient to rotate either direction. The only way you can make that corner now is to place one or two adjacent slopes to auto-form the corner.