Before writing object data to stdout, re-open it in binary mode

Otherwise, you can hit TypeErrors on Python3.

Change-Id: I9a891508886feddac3982ce593bd95130392e035
Closes-Bug: 1775482

openstackclient/api/object_store_v1.py

@@ -378,8 +378,9 @@ class APIv1(api.BaseAPI):
         )
         if response.status_code == 200:
             if file == '-':
+                with os.fdopen(sys.stdout.fileno(), 'wb') as f:
                     for chunk in response.iter_content(64 * 1024):
-                    sys.stdout.write(chunk)
+                        f.write(chunk)
             else:
                 if not os.path.exists(os.path.dirname(file)):
                     if len(os.path.dirname(file)) > 0:

openstackclient/tests/unit/object/v1/test_object_all.py

@@ -241,7 +241,25 @@ class TestObjectSave(TestObjectAll):
 
         parsed_args = self.check_parser(self.cmd, arglist, verifylist)
 
-        with mock.patch('sys.stdout', new=six.BytesIO()) as fake_stdout:
+        class FakeStdout(six.BytesIO):
+            def __init__(self):
+                six.BytesIO.__init__(self)
+                self.context_manager_calls = []
+
+            def __enter__(self):
+                self.context_manager_calls.append('__enter__')
+                return self
+
+            def __exit__(self, *a):
+                self.context_manager_calls.append('__exit__')
+
+        with mock.patch('sys.stdout') as fake_stdout, mock.patch(
+                'os.fdopen', return_value=FakeStdout()) as fake_fdopen:
+            fake_stdout.fileno.return_value = 123
             self.cmd.take_action(parsed_args)
 
-        self.assertEqual(fake_stdout.getvalue(), object_fakes.object_1_content)
+        self.assertEqual(fake_fdopen.return_value.getvalue(),
+                         object_fakes.object_1_content)
+        self.assertEqual(fake_fdopen.mock_calls, [mock.call(123, 'wb')])
+        self.assertEqual(fake_fdopen.return_value.context_manager_calls,
+                         ['__enter__', '__exit__'])

releasenotes/notes/bug-1775482-7ed2a9a8765b313e.yaml

@@ -0,0 +1,6 @@
+---
+fixes:
+  - |
+    Re-open stdout in binary mode before writing object data in
+    ``object save --file -`` command.
+    [Bug `1775482 <https://bugs.launchpad.net/python-openstackclient/+bug/1775482>`_]