Proposed fix for bug #837428.

To test: 
Create an object without an x-timestamp or x-put-timestamp header and request the object with the X-newest header.

Without the patch, the proxy will return a 404 object not found even though the storage nodes return the object to the proxy.

With the patch, the proxy will return the first object received unless an object with a newer timestamp header exists.

swift/proxy/server.py

@@ -645,13 +645,15 @@ class Controller(object):
                 possible_source.status in (200, 206)) or \
                     200 <= possible_source.status <= 399:
                 if newest:
-                    ts = 0
                     if source:
                         ts = float(source.getheader('x-put-timestamp') or
                                    source.getheader('x-timestamp') or 0)
-                    pts = float(possible_source.getheader('x-put-timestamp') or
+                        pts = float(
-                                possible_source.getheader('x-timestamp') or 0)
+                            possible_source.getheader('x-put-timestamp') or
-                    if pts > ts:
+                            possible_source.getheader('x-timestamp') or 0)
+                        if pts > ts:
+                            source = possible_source
+                    else:
                         source = possible_source
                     continue
                 else:

test/unit/proxy/test_server.py

@@ -182,6 +182,8 @@ def fake_http_connect(*code_iter, **kwargs):
                             self.etag or '"68b329da9893e34099c7d8ad5cb9c940"',
                        'x-works': 'yes',
                        }
+            if not self.timestamp:
+                del headers['x-timestamp']
             try:
                 if container_ts_iter.next() is False:
                     headers['x-container-timestamp'] = '1'
@@ -321,8 +323,8 @@ def save_globals():
         proxy_server.http_connect = orig_http_connect
         proxy_server.Controller.account_info = orig_account_info
 
-# tests
 
+# tests
 class TestController(unittest.TestCase):
 
     def setUp(self):
@@ -355,7 +357,8 @@ class TestController(unittest.TestCase):
             partition, nodes = self.controller.account_info(self.account)
             proxy_server.http_connect = fake_http_connect(201,
                                             raise_timeout_exc=True)
-            self.controller._make_request(nodes, partition, 'POST','/','','')
+            self.controller._make_request(nodes, partition, 'POST',
+                                            '/', '', '')
 
     # tests if 200 is cached and used
     def test_account_info_200(self):
@@ -713,7 +716,6 @@ class TestObjectController(unittest.TestCase):
             object_ring=FakeRing())
         monkey_patch_mimetools()
 
-
     def tearDown(self):
         proxy_server.CONTAINER_LISTING_LIMIT = _orig_container_listing_limit
 
@@ -758,6 +760,7 @@ class TestObjectController(unittest.TestCase):
                                                  'text/html', 'text/html']))
             test_content_type('test.css', iter(['', '', '', 'text/css',
                                                 'text/css', 'text/css']))
+
     def test_custom_mime_types_files(self):
         swift_dir = mkdtemp()
         try:
@@ -1079,6 +1082,8 @@ class TestObjectController(unittest.TestCase):
             test_status_map((200, 200, 200), 200, ('1', '3', '2'), '3')
             test_status_map((200, 200, 200), 200, ('1', '3', '1'), '3')
             test_status_map((200, 200, 200), 200, ('3', '3', '1'), '3')
+            test_status_map((200, 200, 200), 200, (None, None, None), None)
+            test_status_map((200, 200, 200), 200, (None, None, '1'), '1')
 
     def test_GET_newest(self):
         with save_globals():
@@ -1102,6 +1107,8 @@ class TestObjectController(unittest.TestCase):
             test_status_map((200, 200, 200), 200, ('1', '3', '2'), '3')
             test_status_map((200, 200, 200), 200, ('1', '3', '1'), '3')
             test_status_map((200, 200, 200), 200, ('3', '3', '1'), '3')
+            test_status_map((200, 200, 200), 200, (None, None, None), None)
+            test_status_map((200, 200, 200), 200, (None, None, '1'), '1')
 
         with save_globals():
             controller = proxy_server.ObjectController(self.app, 'account',
@@ -1124,6 +1131,7 @@ class TestObjectController(unittest.TestCase):
             test_status_map((200, 200, 200), 200, ('1', '3', '2'), '1')
             test_status_map((200, 200, 200), 200, ('1', '3', '1'), '1')
             test_status_map((200, 200, 200), 200, ('3', '3', '1'), '3')
+            test_status_map((200, 200, 200), 200, (None, '1', '2'), None)
 
     def test_POST_meta_val_len(self):
         with save_globals():