Whenever I re-open a world, I have to reset the redstone clocks.

If I have a redstone clock:

/fill ~ ~-1 ~ ~ ~-1 ~ redstone_block
/fill ~ ~1 ~ ~ ~1 ~ stone

I have to reset it each time I re-open the game by replacing the redstone block. I realize they added new repeating command blocks but I think this is a bug.