Add a missing import

cloudbridge/cloud/providers/gce/resources.py

@@ -8,6 +8,7 @@ from cloudbridge.cloud.base.resources import BasePlacementZone
 from cloudbridge.cloud.base.resources import BaseRegion
 from cloudbridge.cloud.base.resources import BaseSecurityGroup
 from cloudbridge.cloud.base.resources import BaseSecurityGroupRule
+from cloudbridge.cloud.interfaces.resources import MachineImageState
 
 # Older versions of Python do not have a built-in set data-structure.
 try:
@@ -680,4 +681,4 @@ class GCEMachineImage(BaseMachineImage):
             # image no longer exists
             cb.log.warning(
                 "googleapiclient.errors.HttpError: {0}".format(http_error))
-            self._gce_image['status'] = "unknown"
+            self._gce_image['status'] = "unknown"