Mistake (don't open)

Hi there!

This looks like a duplicate of MC-130355, because if you were to dig down one or two blocks below the dirt at the bottom of that pocket, you will see that it is actually part of a mineshaft. 

Make sure to do a quick search for your bug before posting it, and then vote for it, comment on it, and follow it. This is the best way for it to be prioritized by Mojang. Making a duplicate post means more work for the volunteers who help out to moderate and clean things up for the developers to look at and fix what needs to be fixed.