Function diff_workspaces_with_contexts 

pub fn diff_workspaces_with_contexts(
    old: &[Package],
    old_system: Option<&System>,
    new: &[Package],
    new_system: Option<&System>,
    old_context: &[Package],
    new_context: &[Package],
    encodings: &[&str],
) -> Result<DiffReport, ContextError>

Compares workspace packages with independent side contexts and, when both sides carry a system, lists the system changes, of which only an instance number change enters the verdict, as breaking (diff_workspaces_with). Missing remote evidence is an error for an explicit podbuf comparison.