Summary

git clone --mirror consistently fails with fatal: expected 'packfile' on non-trivial HuggingFace repos. The same repo clones successfully with --bare.

Reproducer

No auth, no flags, no env vars:

$ git clone --mirror https://huggingface.co/microsoft/phi-1_5 /tmp/phi-mirror
Cloning into bare repository '/tmp/phi-mirror'...
fatal: expected 'packfile'

$ git clone --bare https://huggingface.co/microsoft/phi-1_5 /tmp/phi-bare
Cloning into bare repository '/tmp/phi-bare'...
remote: Enumerating objects: 237, done.
remote: Total 237 (delta 0), reused 0 (delta 0), pack-reused 236 (from 1)
Receiving objects: 100% (237/237), 1.22 MiB | 8.36 MiB/s, done.
Resolving deltas: 100% (128/128), done.

Observations

• --mirror (fetches all refs including refs/pr/*) fails
• --bare (fetches branches and tags only) succeeds
• Tiny repos like prajjwal1/bert-tiny work with both flags — the bug only surfaces on repos with non-trivial content or ref counts

Environment

Reproducible across both client environments we tested:

• macOS 26.4.1 (Build 25E253), git 2.52.0
• Debian GNU/Linux 13 (trixie), git 2.47.3

Reproducible from multiple networks.

Impact

• Internal tooling that relied on --mirror had to switch to --bare.
• The error message is also misleading — it reads like a malformed server response rather than a deliberate rejection of the requested ref set.