There was a custom_execute added into os-brick that takes additional parameters, and now if we just pass in putils.execute it blows up in places we call execute with the new parameters. Short term fix is to just pass in None by default which gives us the custom_execute, under the hood it just uses putils.execute anyway. Change-Id: If5d5fdcf140a557aa2b273e65c0fcdb64aa56f17