I had played a world in which I had a diamond sword and shield. I created a new survival world, and for some time, while the world was still unloaded but my player was in the world, I was holding a diamond sword and shield. That was my first realization of this bug. After that, I tested the bug, and I realized that the world automatically generates while keeping your held items what they were most recently.

What I expected to happen...:
Your default inventory is blank.

"What actually happened...:"
Your default inventory is your previous inventory (which can be easily exploited).

Steps to Replicate:

1. Load a World
2. Save and Quit
3. Load Another World