Handle errors during glance image updates correctly

Before an UnboundLocalError would occur in case an error would happen
during image updates, because of incorrect referencing of a variable.
Moreover the error was muted by exceptions.handle with ignore=True,
and could result in an incorrect success message.
This change removes references to unused image variable and allows
exceptions to be handled by the function, that calls image_update.

Change-Id: I35ea98a146690565582dd9beea62941f97d32474
Closes-Bug: #1464991
(cherry picked from commit 7eb4e3595c)

openstack_dashboard/api/glance.py

@@ -34,7 +34,6 @@ from django.core.files.uploadedfile import TemporaryUploadedFile
 import glanceclient as glance_client
 from six.moves import _thread as thread
 
-from horizon import exceptions
 from horizon.utils import functions as utils
 from horizon.utils.memoized import memoized  # noqa
 from openstack_dashboard.api import base
@@ -111,9 +110,7 @@ def image_list_detailed(request, marker=None, sort_dir='desc',
 def image_update(request, image_id, **kwargs):
     image_data = kwargs.get('data', None)
     try:
-        image = glanceclient(request).images.update(image_id, **kwargs)
-    except Exception:
-        exceptions.handle(request, ignore=True)
+        return glanceclient(request).images.update(image_id, **kwargs)
     finally:
         if image_data:
             try:
@@ -126,7 +123,6 @@ def image_update(request, image_id, **kwargs):
                         '%(file)s (%(e)s)') %
                        dict(file=filename, e=str(e)))
                 LOG.warn(msg)
-    return image
 
 
 def image_create(request, **kwargs):