Command blocks placed on redstone block using /setblock with 'Command' datatag not activating command on placement.
I used the following command:

/setblock 134 64 -182 command_block 0 replace {Command:/fill ~ ~ ~ ~1 ~1 ~1 stained_hardened_clay}

The command block is placed on a redstone block and should have activated on placement. It needs a block update to work, like having something placed next to it or something.

To reproduce this bug:
1. Use /setblock to place a command block. It should have the 'Command' datatag and a regular command inserted there.
2. Have the /setblock command place the command block on top of a redstone block.
3. Place a block next to it to make it activate.