For what it is worth, I have also an Arch install and I can reproduce the problem.
Last time I used my Arch machine for pytorch was two weeks ago and everything was fine (notably, I could run the autograd tests). If I try to run them now, I see the same behaviour described in this issue (everything running but the program not exiting at the end.
Digging through my install logs, I found this:
[2017-04-01 17:21] [ALPM] upgraded glibc (2.24-2 -> 2.25-1)
So it really seems like glibc is problem here.