I'm not completely sure, if this really is a bug, but I think so:
If I teleport a dead player and perform the command /spawnpoint @a on this player by a commandblock, the console will say "Your home bed was missing or obstructed" and spawn him somewhere else (Idk if I can influence this position; to me it seems a bit random).
If a solid block is in the spawnpoint, it will not work.