Mineshafts will never generate chest minecarts where they're exposed to caves

Parts of mineshafts that generate in cave carvers, noise caves, and under overhangs will never generate chest minecarts. This was not the case in 1.9.

To reproduce, use the seed 6434294760392192126 and run the following command:

/execute in minecraft:overworld run tp @p -619 -16 508

The exposed areas of the mineshaft will never generate a chest minecart.