/spawnpoint won't update to chosen coordinates second time unless world file is reloaded

Couldn't find this bug in the list. Sorry if it's a duplicate...

• Create a superflat world (redstone ready)
• setspawn at 56 56 56 (/spawnpoint @a 56 56 56)
• /kill
• set new spawn (/spawnpoint @a -56 56 -656)
• /kill

Player does not spawn at new location (even though command claims spawn is set)

If you reload the world file, then do a spawnpoint command, and die, your spawn is reset. But it only works once per load.

Note, this bug does not occur if you only type /spawnpoint. The bug is specific to typing numerical coordinates.

Is this an intentional change I'm unaware of?