Ensure we check for the right body

Fixes bug #1089544

Change-Id: I8c32d93b7826440f41ae3128f17f41d596d3396e
diff --git a/tempest/common/rest_client.py b/tempest/common/rest_client.py
index 74bd18b..12cf923 100644
--- a/tempest/common/rest_client.py
+++ b/tempest/common/rest_client.py
@@ -213,7 +213,7 @@
         #TODO(afazekas): Make sure we can validate all responses, and the
         #http library does not do any action automatically
         if (resp.status in set((204, 205, 304)) or resp.status < 200 or
-            method.upper() == 'HEAD') and body:
+            method.upper() == 'HEAD') and resp_body:
             raise exceptions.ResponseWithNonEmptyBody(status=resp.status)
 
         #NOTE(afazekas):