Trees can grow through dirt, dark oak trees grow incorrectly if dirt is above the north-west sapling

Steps to Reproduce:

1. Place 4 dark oak saplings in a 2x2 pattern
2. Place a column of 7 dirt above the north-west sapling
3. Bone meal the sapling

Observed Results:
The dark oak tree either grows like this:

or this:

Expected Results:
The dark oak tree should grow like this: