Separate out personality errors and address them in the tests

Also force a build

lib/apiservers/engine/backends/container_proxy.go

@@ -341,7 +341,7 @@ func (c *ContainerProxy) InspectTask(op trace.Operation, handle string, eid stri
 		case *tasks.InspectNotFound:
 			// These error types may need to be expanded. NotFoundError does not fit here.
 			op.Errorf("received a TaskNotFound error during task inspect: %s", err.Payload.Message)
-			return nil, TaskNotFoundError(fmt.Sprintf("container (%s) has been stopped", cid))
+			return nil, TaskPoweredOffError(cid)
 		case *tasks.InspectInternalServerError:
 			op.Errorf("received an internal server error during task inspect: %s", err.Payload.Message)
 			return nil, InternalServerError(err.Payload.Message)
@@ -368,7 +368,7 @@ func (c *ContainerProxy) BindTask(op trace.Operation, handle string, eid string)
 		switch err := err.(type) {
 		case *tasks.BindNotFound:
 			op.Errorf("received TaskNotFound error during task bind: %s", err.Payload.Message)
-			return "", TaskNotFoundError("container (%s) has been stopped")
+			return "", TaskBindPowerError()
 		case *tasks.BindInternalServerError:
 			op.Errorf("received unexpected error attempting to bind task(%s) for handle(%s): %s", eid, handle, err.Payload.Message)
 			return "", InternalServerError(err.Payload.Message)

lib/apiservers/engine/backends/errors.go

@@ -76,6 +76,14 @@ func TaskInspectNotFoundError(msg string) error {
 	return derr.NewRequestNotFoundError(fmt.Errorf("No container was found with exec id: %s", msg))
 }
 
+func TaskBindPowerError() error {
+	return derr.NewRequestNotFoundError(fmt.Errorf("the container has been stopped"))
+}
+
+func TaskPoweredOffError(msg string) error {
+	return derr.NewRequestNotFoundError(fmt.Errorf("container (%s) has been stopped", msg))
+}
+
 func ImageNotFoundError(image, tag string) error {
 	return derr.NewRequestNotFoundError(fmt.Errorf("An image does not exist locally with the tag: %s", image))
 }

tests/test-cases/Group1-Docker-Commands/1-38-Docker-Exec.robot

@@ -27,6 +27,8 @@ Verify Poweroff During Exec Error Message
        Set Test Variable  ${msg3}  Unable to wait for task when container ${containerID} is not running
        Set Test Variable  ${msg4}  the Container(${containerID}) has been shutdown during execution of the exec operation
        Set Test Variable  ${msg5}  container(${containerID}) must be powered on in order to perform the desired exec operation
+       Set Test Variable  ${msg6}  the container has been stopped
+
        Should Contain Any  ${error}  ${msg1}  ${msg2}  ${msg3}  ${msg4}  ${msg5}
 
 Verify No Poweroff During Exec Error Message