Node 1.6.8: NFT mint stability fix

Release notes: https://docs.rougechain.io/running-a-node/release-1.6.8.html

Recommended for every node: fixes a bug that could stop a node producing and importing blocks while processing certain public NFT mints. No consensus change.

sha256 (node): b8c11945ef9c94017e2b1cb46472a4855f609b0ef16cb2fa1532d7a7dabf36e2
sha256 (rougechain CLI): 0df5a526a120eeb12ac77a5a86b6b448bbdf80b371c63db0a4c1427ef22f6870