wither can break blocks while head in bedrock

When the withers head is in a block (in this case bedrock in the nether) it will still break blocks upon spawn explosion. In pc this does not happen so I'm reporting it. And to recreate this: Spawn the wither sideways in a 3 tall place with a piston underneath, when he spawns extend the piston and his head should go into the bedrock. When he explodes he shouldn't break any blocks, but he does. When you do this in pc he will not blow up any blocks while his head is in a block. Either this is a bug, or an unfair feature for Pocket edition alone. Please fix this because the wither in PE is allot harder to kill then the PC wither. Thanks for taking a look at this.