meshio: Cannot detect ugrid

I’m having trouble detecting ugrid for the file attached. Here is what I’m doing:

$ meshio-convert sphere_tetra.1.ugrid sphere.exo
Traceback (most recent call last):
  File "/usr/bin/meshio-convert", line 11, in <module>
    load_entry_point('meshio==2.3.3', 'console_scripts', 'meshio-convert')()
  File "/usr/lib/python3/dist-packages/meshio/cli.py", line 22, in main
    mesh = read(args.infile, file_format=args.input_format)
  File "/usr/lib/python3/dist-packages/meshio/helpers.py", line 128, in read
    file_format = _filetype_from_filename(filename)
  File "/usr/lib/python3/dist-packages/meshio/helpers.py", line 109, in _filetype_from_filename
    ext
AssertionError: Could not deduce file format from extension '.1.ugrid'.

I also tried renaming the file to sphere_tetra.ugrid, but that produces the same problem.

meshio-convert --version
meshio-convert 2.3.3, Python 3.7.3 (default, Dec 20 2019, 18:57:59) [GCC 8.3.0]

sphere_tetra.1.ugrid.txt Rename to sphere_tetra.1.ugrid

Please let me know what I’m doing wrong. Thanks.