Berlin fork causing panic when accessing private state.

[antonydenyer]

Actual behaviour

When sending private transactions on a network that has the berlin fork enabled a panic is being fired at https://github.com/ConsenSys/quorum/blob/fbfb5dd12a8c2b8abd053f858ef539ab38196b75/core/vm/operations_acl.go#L66

Steps to reproduce the behaviour

Using https://www.npmjs.com/package/quorum-dev-quickstart/v/0.1.3 run the privacy transaction example.