A logical novelty. Black makes use of the pin  to trade the dark-squared bishops.
1. c2c4  1... c7c5  2. g2g3  2... g7g6  3. f1g2  3... f8g7  4. b1c3  4... b8c6  5. g1f3  5... d7d6  6. e1g1  6... c8f5  7. b2b3  7... g8f6  8. c1b2 