the repo on disk is expected to be less than the sum of the size of each of its revisions.
For example, here `bert-base-cased` has 2 revisions of 1.4G and 1.5G but the total disk
usage is only 1.9G.  
```text
➜ huggingface-cli scan-cache -v
REPO ID                     REPO TYPE REVISION                                 SIZE ON DISK NB FILES LAST_MODIFIED REFS        LOCAL PATH