Merge pull request #20 from OffchainLabs/kolbyml/add-overwriteContractCode

ArbDebug: add overwriteContractCode interface

Author: KolbyML

ArbDebug.sol

@@ -12,6 +12,12 @@ interface ArbDebug {
     /// @notice Caller becomes a chain owner
     function becomeChainOwner() external;
 
+    /// @notice Overwrite an existing contract's code
+    function overwriteContractCode(
+        address target,
+        bytes calldata newCode
+    ) external returns (bytes memory oldCode);
+
     /// @notice Emit events with values based on the args provided
     function events(
         bool flag,