Fetching a Repository with special branch names breaks on Windows

[calyptobai]

Current behavior 😯

Calling fetch_only on Windows for a repository with a branch named foo<1.0 fails due to:

Fetch(UpdateRefs(EditReferences(FileTransactionCommit(DeleteReference { full_name: "refs/remotes/origin/foo<1.0", err: Os { code: 123, kind: InvalidFilename, message: "The filename, directory name, or volume label syntax is incorrect." } }))))

Expected behavior 🤔

I would expect this to work on Windows, given that foo<1.0 is a well-formed name according to git's ref naming rules.

Steps to reproduce 🕹

1. Use Windows
2. Try to PrepareFetch and fetch_only for https://github.com/calyptobai/gix-fetch-win-fail.git

[Byron]

Thanks for reporting!

git seems to be able to do it by writing packed-refs right away.

# pack-refs with: peeled fully-peeled sorted 
2f3c410f1900acbf8bb3d29f008d1f9b57103053 refs/remotes/origin/foo<1.0
2f3c410f1900acbf8bb3d29f008d1f9b57103053 refs/remotes/origin/main

gix also does that which works around issues around case-insensitivity for example, but that doesn't seem to kick in here. Instead it tries to create a file with such a name and fails.

The goal here would to figure out why it's not writing straight to packed refs.

[Byron]

A quick investigation shows that…

• gix (CLI)` already asks to write packed refs only - this doesn't seem to fully kick-in
• By default, this setting won't write packed refs by default which on windows and/or for performance should probably rather be 'always'.
• gix-ref will still try to obtain a lock on each of the refs individually even when moving them into a packed-ref, apparently, even though it shouldn't have to do that.

So in this case, it's probably these the last two points to adjust and investigate.