Treats a block as if it were received before others with the same work. Cannot be used to undo a previous call.
blockhashstringREQUIREDcurl --user myuser --data-binary '{"jsonrpc":"1.0","id":"1","method":"preciousblock","params":["blockhash"]}' -H 'content-type:text/plain;' http://127.0.0.1:8332/null