update to initialize the Environment map

agent/agent.go

@@ -210,6 +210,9 @@ func (a *Agent) exec(spec *yaml.Config, payload *queue.Work, cancel <-chan bool)
 			}
 			// updates the build status passed into each container. I realize this is
 			// a bit out of place and will work to resolve.
+		        if pipeline.Head().Environment == nil {
+				pipeline.Head().Environment = make(map[string]string)
+			}
 			pipeline.Head().Environment["DRONE_BUILD_STATUS"] = status
 
 			if !pipeline.Head().Constraints.Match(