I don't think it's a duplicate of that bug; based on looking at the code for 1.4.7 (MCP's onNeighborBlockChange() function in BlockDispenser.java), I think droppers/dispensers activating when the block at y+1 of them is powered is intended. If that's intended, the bug is that dispensers/droppers receive power differently from levers/buttons than dust/torches/repeaters (and comparators that I just checked now).
Joe Pelkey
I don't think it's a duplicate of that bug; based on looking at the code for 1.4.7 (MCP's onNeighborBlockChange() function in BlockDispenser.java), I think droppers/dispensers activating when the block at y+1 of them is powered is intended. If that's intended, the bug is that dispensers/droppers receive power differently from levers/buttons than dust/torches/repeaters (and comparators that I just checked now).