Wally server consistently crashes due to "corrupted loose reference file"

[NobleDraconian]

Currently, as of v0.3.2, the wally server consistently crashes when attempting to point it to a github repository for its index.

To reproduce:

1. Create a fresh blank repository through github's web UI, name it wally-index
2. Compile the wally server binary via cargo build --release.
3. Create the environment variables:

export WALLY_INDEX_URL="https://github.com/scope/wally-index"
export WALLY_AUTH="{type=api-key,value=herebedragons}"
export WALLY_GITHUB_TOKEN="tokenhere"
export WALLY_STORAGE="{type=local}"

4. Run the wally server (./wally-registry-backend)
5. Observe that wally crashes because of a "corrupted loose reference file", despite the index repository being freshly created on github and not touched by any local machines:
   

[NobleDraconian]

This seems to occur if the index repository has a master branch, instead of a main branch. Renaming master to main fixes the issue.