Ensure JSON isn't read on no HTTP response body

This patch moves the json.loads(body) call in the
HTTP response handling to after the check for non-
200-300 return codes. This gets rid of the
ValueError exception raise when you hit, for instance,
a 400 or 404.

Also changes a number of logger.exception() calls to
logger.debug() calls, since some exceptions are expected
and should not be logged as exceptions per-se.

fixes LP bug#1067512

Change-Id: If66fb1846ddc19da5bc2f15c6e0dd09019a56932

keystoneclient/client.py

@@ -127,6 +127,13 @@ class HTTPClient(httplib2.Http):
                                                      **request_kwargs)
         self.http_log_resp(resp, body)
 
+        if resp.status in (400, 401, 403, 404, 408, 409, 413, 500, 501):
+            _logger.debug("Request returned failure status.")
+            raise exceptions.from_response(resp, body)
+        elif resp.status in (301, 302, 305):
+            # Redirected. Reissue the request to the new location.
+            return self.request(resp['location'], method, **kwargs)
+
         if body:
             try:
                 body = json.loads(body)
@@ -136,13 +143,6 @@ class HTTPClient(httplib2.Http):
             _logger.debug("No body was returned.")
             body = None
 
-        if resp.status in (400, 401, 403, 404, 408, 409, 413, 500, 501):
-            _logger.exception("Request returned failure status.")
-            raise exceptions.from_response(resp, body)
-        elif resp.status in (301, 302, 305):
-            # Redirected. Reissue the request to the new location.
-            return self.request(resp['location'], method, **kwargs)
-
         return resp, body
 
     def _cs_request(self, url, method, **kwargs):

keystoneclient/v2_0/client.py

@@ -106,9 +106,9 @@ class Client(client.HTTPClient):
             self._extract_service_catalog(self.auth_url, raw_token)
             return True
         except (exceptions.AuthorizationFailure, exceptions.Unauthorized):
+            _logger.debug("Authorization Failed.")
             raise
         except Exception, e:
-            _logger.exception("Authorization Failed.")
             raise exceptions.AuthorizationFailure("Authorization Failed: "
                                                   "%s" % e)