core: allow for config override on non-mainnet networks

core/genesis.go

@@ -203,15 +203,9 @@ func SetupGenesisBlockWithOverride(db ethdb.Database, genesis *Genesis, override
 		}
 	}
 	// Get the existing chain configuration.
-	overrides := false
 	newcfg := genesis.configOrDefault(stored)
 	if overrideArrowGlacier != nil {
 		newcfg.ArrowGlacierBlock = overrideArrowGlacier
-		overrides = true
-	}
-	if overrideTerminalTotalDifficulty != nil {
-		newcfg.TerminalTotalDifficulty = overrideTerminalTotalDifficulty
-		overrides = true
 	}
 	if err := newcfg.CheckConfigForkOrder(); err != nil {
 		return newcfg, common.Hash{}, err
@@ -222,10 +216,14 @@ func SetupGenesisBlockWithOverride(db ethdb.Database, genesis *Genesis, override
 		rawdb.WriteChainConfig(db, stored, newcfg)
 		return newcfg, stored, nil
 	}
+
+	if overrideTerminalTotalDifficulty != nil {
+		storedcfg.TerminalTotalDifficulty = overrideTerminalTotalDifficulty
+	}
 	// Special case: don't change the existing config of a non-mainnet chain if no new
 	// config is supplied. These chains would get AllProtocolChanges (and a compat error)
 	// if we just continued here.
-	if !overrides && genesis == nil && stored != params.MainnetGenesisHash {
+	if genesis == nil && stored != params.MainnetGenesisHash {
 		return storedcfg, stored, nil
 	}
 	// Check config compatibility and write the config. Compatibility errors