1.8.1

This releases includes a fix to a bug discovered by @alialabbas, which has been introduced in 1.3.0 with the contract deduplication optimization.

The contract deduplication optimization would eliminate some contracts unduly, because the optimizer wrongly deemed them equivalent to another contract already applied to the same value. This could result in some record contracts being potentially silently ignored in specific conditions, letting wrong values slip through.

See #2041 for more details.