Wrong MPI messages ht.int16

[mtar]

Description
A clear and concise description of the bug and the associated functionality.

MPI messages are compromised, when int16 tensors are communicated

To Reproduce
Steps to reproduce the behavior:

1. Which module/class/function is affected?
   int16 tensors, mpi functions

2. What are the circumstances under which the bug appears?
   MPI communication with int16 arrays

3. What is the exact error-message/errorous behavious?
   erroneous received messages; error message on 4 elements (see example)

Expected behavior
A clear and concise description of what you expected to happen.
Getting same message

Illustrative
If applicable, add screenshots or minimal examples to help explain your problem.

a = ht.array([[4,5,6,7],[6,7,8,9]], split=0, dtype=ht.int16)
if a.comm.rank == 0:
	print(a.comm.rank, a)
	a.comm.Send(a, dest=1)
elif a.comm.rank == 1:
	b = ht.empty((1,4), a.dtype)
	a.comm.Recv(b, source=0)
	print(a.comm.rank, b)

$ mpirun -n 2 python bug.py 
0 tensor([[4, 5, 6, 7]], dtype=torch.int16)
1 tensor([[4, 0, 6, 7]], dtype=torch.int16)
malloc_consolidate(): invalid chunk size
[ZAM:10232] *** Process received signal ***
[ZAM:10232] Signal: Aborted (6)
[ZAM:10232] Signal code:  (-6)
[ZAM:10232] [ 0] /lib/x86_64-linux-gnu/libc.so.6(+0x3ef20)[0x7f516f8e3f20]
[ZAM:10232] [ 1] /lib/x86_64-linux-gnu/libc.so.6(gsignal+0xc7)[0x7f516f8e3e97]
[ZAM:10232] [ 2] /lib/x86_64-linux-gnu/libc.so.6(abort+0x141)[0x7f516f8e5801]
[ZAM:10232] [ 3] /lib/x86_64-linux-gnu/libc.so.6(+0x89897)[0x7f516f92e897]
[ZAM:10232] [ 4] /lib/x86_64-linux-gnu/libc.so.6(+0x9090a)[0x7f516f93590a]
[ZAM:10232] [ 5] /lib/x86_64-linux-gnu/libc.so.6(+0x90bae)[0x7f516f935bae]
[ZAM:10232] [ 6] /lib/x86_64-linux-gnu/libc.so.6(+0x947d8)[0x7f516f9397d8]
[ZAM:10232] [ 7] /lib/x86_64-linux-gnu/libc.so.6(__libc_malloc+0x27d)[0x7f516f93c2ed]
[ZAM:10232] [ 8] python[0x5ac0b5]
[ZAM:10232] [ 9] python[0x56a894]
[ZAM:10232] [10] python[0x56bee3]
[ZAM:10232] [11] python(PyDict_SetItemString+0x153)[0x571633]
[ZAM:10232] [12] python(PyImport_Cleanup+0x76)[0x4f3256]
[ZAM:10232] [13] python(Py_FinalizeEx+0x5e)[0x6383ce]
[ZAM:10232] [14] python(Py_Main+0x395)[0x639435]
[ZAM:10232] [15] python(main+0xe0)[0x4b0f40]
[ZAM:10232] [16] /lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xe7)[0x7f516f8c6b97]
[ZAM:10232] [17] python(_start+0x2a)[0x5b2fda]
[ZAM:10232] *** End of error message ***
--------------------------------------------------------------------------
mpirun noticed that process rank 1 with PID 0 on node ZAM exited on signal 6 (Aborted).
--------------------------------------------------------------------------

Version Info
Which version are you using?
master

Additional comments
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