The menu shows "Branch unknown" for every submodule, whatever it has
checked out. A submodule has no .git directory; its .git is a file
naming the directory, and for a submodule git writes that name relative
to the submodule. We hand it to os.ReadFile unchanged, so it resolves
against lazygit's own working directory and the read fails. A worktree
created with --relative-paths (or with worktree.useRelativePaths set)
gets a relative name too, and fails the same way.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>