Uses None instead of mutable dicts for default function arguments

Forgot to update dicts with changeset I4a89afad, which updated lists.

Change-Id: Ieca71b9c90ee5dae83a43f6851b6b8b2924bcb8e
Fixes: bug 1174809

swift/common/direct_client.py

@@ -180,7 +180,10 @@ def direct_get_container(node, part, account, container, marker=None,
 
 
 def direct_delete_container(node, part, account, container, conn_timeout=5,
-                            response_timeout=15, headers={}):
+                            response_timeout=15, headers=None):
+    if headers is None:
+        headers = {}
+
     path = '/%s/%s' % (account, container)
     headers['X-Timestamp'] = normalize_timestamp(time())
     with Timeout(conn_timeout):
@@ -237,7 +240,7 @@ def direct_head_object(node, part, account, container, obj, conn_timeout=5,
 
 
 def direct_get_object(node, part, account, container, obj, conn_timeout=5,
-                      response_timeout=15, resp_chunk_size=None, headers={}):
+                      response_timeout=15, resp_chunk_size=None, headers=None):
     """
     Get object directly from the object server.
 
@@ -253,6 +256,9 @@ def direct_get_object(node, part, account, container, obj, conn_timeout=5,
     :returns: a tuple of (response headers, the object's contents) The response
               headers will be a dict and all header names will be lowercase.
     """
+    if headers is None:
+        headers = {}
+
     path = '/%s/%s/%s' % (account, container, obj)
     with Timeout(conn_timeout):
         conn = http_connect(node['ip'], node['port'], node['device'], part,
@@ -378,7 +384,7 @@ def direct_post_object(node, part, account, container, name, headers,
 
 
 def direct_delete_object(node, part, account, container, obj,
-                         conn_timeout=5, response_timeout=15, headers={}):
+                         conn_timeout=5, response_timeout=15, headers=None):
     """
     Delete object directly from the object server.
 
@@ -391,6 +397,9 @@ def direct_delete_object(node, part, account, container, obj,
     :param response_timeout: timeout in seconds for getting the response
     :returns: response from server
     """
+    if headers is None:
+        headers = {}
+
     path = '/%s/%s/%s' % (account, container, obj)
     headers['X-Timestamp'] = normalize_timestamp(time())
     with Timeout(conn_timeout):

swift/common/swob.py

@@ -925,7 +925,7 @@ class Response(object):
     charset = _resp_charset_property()
     app_iter = _resp_app_iter_property()
 
-    def __init__(self, body=None, status=200, headers={}, app_iter=None,
+    def __init__(self, body=None, status=200, headers=None, app_iter=None,
                  request=None, conditional_response=False, **kw):
         self.headers = HeaderKeyDict(
             [('Content-Type', 'text/html; charset=UTF-8')])
@@ -939,7 +939,8 @@ class Response(object):
             self.environ = request.environ
         else:
             self.environ = {}
-        self.headers.update(headers)
+        if headers:
+            self.headers.update(headers)
         for key, value in kw.iteritems():
             setattr(self, key, value)