Early die if on image gets killed

The Images reaches the 'killed' status only on an
unrecoverable error, any further wait is in vain.

The wait method will raise an exception on the killed state.

Change-Id: I392674c872d7f2354a2a2d338e14630b211cf12b
diff --git a/tempest/exceptions.py b/tempest/exceptions.py
index 8d05fd8..67406b0 100644
--- a/tempest/exceptions.py
+++ b/tempest/exceptions.py
@@ -81,6 +81,10 @@
     message = "Server %(server_id)s failed to build and is in ERROR status"
 
 
+class ImageKilledException(TempestException):
+    message = "Image %(image_id)s 'killed' while waiting for %(status)s"
+
+
 class AddImageException(TempestException):
     message = "Image %(image_id)s failed to become ACTIVE in the allotted time"
 
diff --git a/tempest/services/image/v1/json/image_client.py b/tempest/services/image/v1/json/image_client.py
index 1921d78..41b9e81 100644
--- a/tempest/services/image/v1/json/image_client.py
+++ b/tempest/services/image/v1/json/image_client.py
@@ -265,9 +265,12 @@
                 LOG.info('Value transition from "%s" to "%s"'
                          'in %d second(s).', old_value,
                          value, dtime)
-            if (value == status):
+            if value == status:
                 return value
 
+            if value == 'killed':
+                raise exceptions.ImageKilledException(image_id=image_id,
+                                                      status=value)
             if dtime > self.build_timeout:
                 message = ('Time Limit Exceeded! (%ds)'
                            'while waiting for %s, '