Minecraft wiki entry for Block_update, associated text: Exception
However, there are some exceptions:
Lighting a nether portal does not send PP update.
A nether portal generating does not send PP update.
Changing block state with debug stick does not send PP update.
Shulker boxes sends general PP updates when beginning to open/close or complete openning/closing.
When a redstone wire is placed, destroyed, replaced, or its blockstate is changed, for any block that the redstone wire points horizontally to, if it is not a redstone wire, then the game also sends PP updates to the block above it and the block below it. However, it does not send PP update to an observer.
Pistons and beds have more complex updates.