ticking crash, dispenser with flintsteel facing down, next to obsidian block

Game crashes when the dispenser attempts to spark a fire with the flint and steel when there is two air blocks it and there is a block of obsidian next to and one block below it.

It is easy to recreate. You just need 1 block of obsidian, a dispenser, a lever to actuate the dispenser and a flint+steel in the dispenser's inventory.  Make sure the dispenser has at least two blocks of air below it so that it can't start the fire. Activate the lever and the game immediately crashes.

 

a possible patch