Oak Roof trees drop spruce saplings, instead of Oak Roof saplings.

Oak Roof trees drop spruce saplings, instead of Oak Roof saplings. I was in creative, blew up an Oak Roof tree with TNT, and Spruce saplings dropped instead.

What I expected to happen was...:
Oak Roof saplings would drop from Oak Roof trees.

What actually happened was...:
Spruce saplings dropped from Oak Roof trees

Steps to Reproduce:
1. Ignite TNT atop an Oak Roof tree
2. Collect the saplings that are a result of the explosion.
3. Notice these saplings are Spruce saplings, when they should be Oak Roof saplings.