when shifting, flying (in creative) and holding down the place button trying to place a block that has air beneath it you also place up to 2 extra blocks beneath the block you placed
How to reproduce
1. go in creative mode
2. start flying
3. shift (by standing on a block, NOT by holding space at the same time)
4. hold the place button to place a block wich has air beneath it

expected result: you just place one block
result: you place 2 extra blocks underneath the block