[MC-59518] Command block previous output has unused / not working feature

1. Perform this command with a command block:
```
/give @p stone
```
2. Place a command block above the first command block and perform this:
```
/blockdata ~ ~-1 ~ {}
```

You will get this last output:

[14:35:38] The data tag did not change: {
	Command:"/give @p stone ",
	id:"Control",
	TrackOutput:1b,
	LastOutput:"{
		\"extra\":[{
			\"translate\":\"commands.give.success\",
			\"with\":[{
				\"color\":\"white\",
				\"hoverEvent\":{
					\"action\":\"show_item\",
					\"value\":\"{
						id:\\"minecraft:stone\\",
						Damage:0s,Count:1b,
					}
				\"},
				\"extra\":[
					\"Stone\",
				\"]
			\"],
			\"text\":\"[\"},
				\"1\",
				\"Marcono1234\"
			]
		}],
	\"text\":\"[14:35:33] 
	\"}",
	CustomName:"@",SuccessCount:1,z:609,y:56,x:1233,
}

Like you can see there is a hoverEvent which doesn't work yet

This is also for example with achievements (there you get the "color:dark_purple" which is not working, while §5 would work)