[BUG] Atomicity Test Failed Process 1: read_buf[2047] is 0, should be 5

[hyoklee]

Describe the bug See

https://forum.hdfgroup.org/t/hdf5-1-12-1-make-check-atomiticity-test-failure/9701

Expected behavior

Pass test.

Platform (please complete the following information)

• HDF5 version: 1.12.1 and develop
• OS and version: Ubuntu 20.04 and latest
• Compiler and version: gcc
• Build system (e.g. CMake, Autotools) and version: autotools
• Any configure options you specified: --enable-parallel
• MPI library and version (parallel HDF5): sudo apt-get libopenmpi-dev

Additional context

https://github.com/hyoklee/hdf5/actions/workflows/linux-auto.yml