Is `--gzip` supposed to fetch compressed files or trigger local compression?

[ezherman]

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Describe the bug
I have compared rehydration with and without --gzip, expecting this option to fetch a compressed genome and to therefore have a shorter runtime. Instead I am finding --gzip adds to the runtime, suggesting compression is happening on my machine. I am opening this issue to confirm: is --gzip supposed to fetch compressed files?

To Reproduce

datasets download genome accession GCF_000001405.40 --dehydrated --filename human_GRCh38_dataset.zip
unzip human_GRCh38_dataset.zip -d my_human_dataset
time datasets rehydrate --directory my_human_dataset/ --gzip
time datasets rehydrate --directory my_human_dataset/

Expected behavior

time datasets rehydrate --directory my_human_dataset/ --gzip
Found 1 of 1 files for rehydration
Completed 1 of 1 [================================================] 100%

real	5m39.572s
user	0m4.918s
sys	0m10.745s

time datasets rehydrate --directory my_human_dataset/
Found 1 of 1 files for rehydration
Completed 1 of 1 [================================================] 100%

real	4m46.089s
user	0m28.370s
sys	0m10.848s

Thanks!