Merge pull request #4851 from filecoin-project/fix/daemon-test-mode-r…

…estart

Truncate genesis file before generating

node/modules/testing/genesis.go

@@ -81,7 +81,7 @@ func MakeGenesis(outFile, genesisTemplate string) func(bs dtypes.ChainBlockstore
 
 			fmt.Printf("GENESIS MINER ADDRESS: t0%d\n", genesis2.MinerStart)
 
-			f, err := os.OpenFile(outFile, os.O_CREATE|os.O_WRONLY, 0644)
+			f, err := os.OpenFile(outFile, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644)
 			if err != nil {
 				return nil, err
 			}