When I pass the end portal for come back in the overworld without aving slepping in a bed, I spawn in the end. The same thing happened when I die. I stay blocked here and I can't come back in the overworld with the help of the command. 

here a link to a video that show you what happen : https://www.youtube.com/watch?v=dqji_RO9JoU&feature=youtu.be

(edit : it seem to happen in the nether too, I spawn in 0/0 when I die in the nethe  without bed