Compare against 'RequestIdProxy.wrapped'

Due to the 'glanceclient.common.utils.add_req_id_to_object' decorator,
an instance of 'glanceclient.common.utils.RequestIdProxy' is returned
for most calls in glanceclient. If we wish to compare to None, we have
to compare the contents of this wrapper and not the wrapper itself.

Unit tests are updated to highlight this.

Change-Id: I7dadf32d37ac2bda33a92c71d5882e9f23e38a82
Closes-Bug: #1736759

glanceclient/tests/unit/v2/test_shell_v2.py

@@ -581,11 +581,10 @@ class ShellV2Test(testtools.TestCase):
         args = self._make_args(
             {'id': 'IMG-01', 'file': 'test', 'progress': True})
 
-        with mock.patch.object(self.gc.images, 'data') as mocked_data:
-            def _data():
-                for c in 'abcedf':
-                    yield c
-            mocked_data.return_value = utils.IterableWithLength(_data(), 5)
+        with mock.patch.object(self.gc.images, 'data') as mocked_data, \
+                mock.patch.object(utils, '_extract_request_id'):
+            mocked_data.return_value = utils.RequestIdProxy(
+                [c for c in 'abcdef'])
 
             test_shell.do_image_download(self.gc, args)
             mocked_data.assert_called_once_with('IMG-01')

glanceclient/v2/shell.py

@@ -353,7 +353,7 @@ def do_image_download(gc, args):
         msg = "Unable to download image '%s'. (%s)" % (args.id, e)
         utils.exit(msg)
 
-    if body is None:
+    if body.wrapped is None:
         msg = ('Image %s has no data.' % args.id)
         utils.exit(msg)