Crafting with shift-right-click destroys fractional outputs (e.g. 1-3 planks) when overfilling inventory

When my inventory is otherwise full, 31 oak wood planks are at my feet and I put 9 oak logs on the crafting grid (and automatically pick up the 31 planks in their place) and shift-right-click the crafting output, the stack of 31 becomes a stack of 64, but this only creates 33 plank blocks instead of the usual 36. The other 3 seemingly disappear. I'd expect the shift-right-click to either craft only 8 logs into planks in this case, leaving one on the grid, or else craft all 9 and drop the 3 plank blocks I can't carry at my feet.