Abandoned mineshafts generated Oak Planks

In the wiki it said "Abandoned mineshaft will generate Dark Oak Planks", But I found an issue. Its generated Oak Planks instead.

Step to reproduce :
1. Create world using seed 5269664457922051499
2. You will spawn at the Mesa Biome and looking at for mineshaft around that area.
3. If you follow this coordinate -55 80 195. Mineshaft generate Dark Oak Planks, its default!?
4. And now try to use this command. /tp @p 5772 100 1773
5. Go to coordinate (Don't use /tp command) 5702 27 1943
6. You will see mineshaft generated Oak Planks like a screenshot.

Sorry if this feature is intended and duplicated.