Function unified_diff_histogram_hunks_only 

pub fn unified_diff_histogram_hunks_only(
    old_content: &str,
    new_content: &str,
    context_lines: usize,
    inter_hunk_context: usize,
) -> String

Unified diff hunks for Git’s histogram algorithm (no --- / +++ lines).

Used by --no-index when whitespace normalization is off so the patch matches upstream Git.