Resetting a world's icon via the Edit button in the Single-player menu causes it to turn into a random texture

Select a world via the Single-player menu, click "Edit" and "Reset Icon".
The icon resets to a random texture, in my case, the Sea Turtle mob texture.

Due to file size limitations, a demonstration has been uploaded to YouTube:
MC-187707

This also relates to & appears to be a new issue:
MC-170468