1) Only allow a single statediff of a block hash+number at a time.
2) Do not state diff if that block hash+number already exists in the DB.
INFO [06-01|05:26:11.063] Not writing, statediff in progress. number=605 hash=0x336e7cb623164e70dca3dc01c3dabf1a5e8af25f7c26db0e00eedc3e9c8c959d
INFO [06-01|05:26:11.083] Not writing, statediff already done. number=600 hash=0x13399d30c79e8d32d00d6cb4ceb545a0467a61c58474986b6b74651d903a12ff
Related to https://github.com/cerc-io/go-ethereum/issues/367.
Add two checks:
1) Only allow a single statediff of a block hash+number at a time.
2) Do not state diff if that block hash+number already exists in the DB.