The placement of a sign does not cause block updates. I proved this by cancelling a water stream, with a BUD-switch (see images) and melted, solid water.
The placement of a sign does not cause block updates. I proved this by cancelling a water stream, with a BUD-switch (see images) and melted, solid water.
Try this. Place a block of ice then a block of glowstone beside it, and wait for the ice to melt (it should not flow and require a block update). Then place a sign next to the water block. Does it begin to flow?