Package conflicts trying to install jpegdupes package

[Skip Montanaro]

I'd like to use the jpegdupes package <https://pypi.org/project/jpegdupes/> but
can't seem to get past compilation issued related to jpegtrans-cffi.
Attempts to install any available versions on my XUbuntu system crap out
with this C compiler error message:

     In file included from
jpegtran/__pycache__/_cffi__xd2d84bdexcdb1023.c:267:
    src/epeg_private.h:71:17: warning: ‘_jpeg_init_source’ declared
‘static’ but never defined [-Wunused-function]
       71 | METHODDEF(void) _jpeg_init_source(j_decompress_ptr cinfo);
          |                 ^~~~~~~~~~~~~~~~~
    src/epeg_private.h:72:20: warning: ‘_jpeg_fill_input_buffer’ declared
‘static’ but never defined [-Wunused-function]
       72 | METHODDEF(boolean) _jpeg_fill_input_buffer(j_decompress_ptr
cinfo);
          |                    ^~~~~~~~~~~~~~~~~~~~~~~
    src/epeg_private.h:73:17: warning: ‘_jpeg_skip_input_data’ declared
‘static’ but never defined [-Wunused-function]
       73 | METHODDEF(void) _jpeg_skip_input_data(j_decompress_ptr cinfo,
long num_bytes);
          |                 ^~~~~~~~~~~~~~~~~~~~~
    src/epeg_private.h:74:17: warning: ‘_jpeg_term_source’ declared
‘static’ but never defined [-Wunused-function]
       74 | METHODDEF(void) _jpeg_term_source(j_decompress_ptr cinfo);
          |                 ^~~~~~~~~~~~~~~~~
    src/epeg_private.h:76:17: warning: ‘_jpeg_init_destination’ declared
‘static’ but never defined [-Wunused-function]
       76 | METHODDEF(void) _jpeg_init_destination(j_compress_ptr cinfo);
          |                 ^~~~~~~~~~~~~~~~~~~~~~
    src/epeg_private.h:77:20: warning: ‘_jpeg_empty_output_buffer’ declared
‘static’ but never defined [-Wunused-function]
       77 | METHODDEF(boolean) _jpeg_empty_output_buffer (j_compress_ptr
cinfo);
          |                    ^~~~~~~~~~~~~~~~~~~~~~~~~
    src/epeg_private.h:78:17: warning: ‘_jpeg_term_destination’ declared
‘static’ but never defined [-Wunused-function]
       78 | METHODDEF(void) _jpeg_term_destination (j_compress_ptr cinfo);
          |                 ^~~~~~~~~~~~~~~~~~~~~~

    ...
This seems like a rather odd error message for a presumably sort-of-stable
PyPI package. Looking at the version dependencies I see 2.6, 2.7, 3.3 or
PyPy. I thought nmybe I needed to try with Python2... Create a Conda
environment, attempt to install jpegdupes, only to discover it's Python 3
only.

So, I'm kind of stuck. Maybe I need to install Python 3.3 and try that? Any
other ideas?

Thx,

Skip