data_dir keeps prefacing cwd and hence downloading voice again unless cwd IS the voice directory

[troff01]

I have voices downloaded to a folder /mnt/data/Speech and debug text prints as follows:

DEBUG:__main__:Namespace(model='en_GB-jenny_dioco-medium', config=None, output_file=None, output_dir='/mnt/data/Speech', output_raw=True, speaker=None, length_scale=None, noise_scale=None, noise_w=None, cuda=False, sentence_silence=0.0, data_dir=['/mnt/data/Speech', '/mnt/data/Speech'], download_dir='/mnt/data/Speech', update_voices=True, debug=True)

As per instruction, voices.json updates. If I change cwd to Desktop directory, the following occurs:

DEBUG:__main__:Namespace(model='en_GB-aru-medium', config=None, output_file=None, output_dir='/mnt/data/Speech', output_raw=True, speaker=None, length_scale=None, noise_scale=None, noise_w=None, cuda=False, sentence_silence=0.0, data_dir=['/home/p/Desktop', '/mnt/data/Speech'], download_dir='/mnt/data/Speech', update_voices=True, debug=True)

Regardless of how data-directory is specified, whether I specify a download-directory or not, it will KEEP DOWNLOADING voices - either to download-directory, or to cwd.

The call is being executed so:
echo "${line}" | piper --debug --model "${VOICE}" --output-raw -d "${SPEECHDIR}" --data-dir "${SPEECHDIR}" --output-dir "${SPEECHDIR}" --download-dir "${SPEECHDIR}" | aplay -r ${RATE} -f S16_LE -t raw -

I have also tried specifying directories with --OPTION-HERE="${SPEECHDIR}" with an equals rather than a space; this makes no difference to the result; data_dir=[] always prepends cwd and hence:

DEBUG:__main__:Namespace(model='en_GB-vctk-medium', config=None, output_file=None, output_dir='/mnt/data/Speech', output_raw=True, speaker=None, length_scale=None, noise_scale=None, noise_w=None, cuda=False, sentence_silence=0.0, data_dir=['/home/p/Desktop', '/mnt/data/Speech'], download_dir='/mnt/data/Speech', update_voices=False, debug=True)
DEBUG:piper.download:Loading /mnt/data/Speech/voices.json
DEBUG:piper.download:Checking /home/p/Desktop/en_GB-vctk-medium.onnx
DEBUG:piper.download:Missing /home/p/Desktop/en_GB-vctk-medium.onnx
DEBUG:piper.download:Checking /home/p/Desktop/en_GB-vctk-medium.onnx.json
DEBUG:piper.download:Missing /home/p/Desktop/en_GB-vctk-medium.onnx.json
DEBUG:piper.download:Downloading https://huggingface.co/rhasspy/piper-voices/resolve/v1.0.0/en/en_GB/vctk/medium/en_GB-vctk-medium.onnx.json to /mnt/data/Speech/en_GB-vctk-medium.onnx.json
INFO:piper.download:Downloaded /mnt/data/Speech/en_GB-vctk-medium.onnx.json (https://huggingface.co/rhasspy/piper-voices/resolve/v1.0.0/en/en_GB/vctk/medium/en_GB-vctk-medium.onnx.json)
DEBUG:piper.download:Downloading https://huggingface.co/rhasspy/piper-voices/resolve/v1.0.0/en/en_GB/vctk/medium/en_GB-vctk-medium.onnx to /mnt/data/Speech/en_GB-vctk-medium.onnx
INFO:piper.download:Downloaded /mnt/data/Speech/en_GB-vctk-medium.onnx (https://huggingface.co/rhasspy/piper-voices/resolve/v1.0.0/en/en_GB/vctk/medium/en_GB-vctk-medium.onnx)