Specify SHA when "Preparing working directory" when running plugin

Hi Paula,

To expand a bit more, the pipeline in question is setting up two instances to perform an automated analysis. The plugin we’re using currently references a local configuration file, but this file needs to match the version being deployed. I was hoping there was a way to override the branch that the “prepare working directory” step checks out to resolve my particular issue. I think I’ll try to checkout the branch prior to calling the plugin instead and skip the checkout as mentioned here.