Summon firework rocket

(I am using an ASUS ZenPad)
when putting a command block on repeat and on always active, then typing the command '/summon fireworks_rocket ~ ~ ~ ' then leaving it run, after exiting the game or saving and quit while it is still running, it stays in the game. After coming back into the game, the firework effect is infinitely running. Every time you leave out of the game suddenly, it gets bigger and bigger, even after get rid of the command block and typing '/kill @e'
This is very annoying, please help. You can test it for yourself. This is on the full release of the 1.2 update.
Below shows how even when I changed the command to needs redstone, it still works.

Update: when adding lava on the block that the firework entities spawn, it ignites them, then summons millions of entities as shown.