Open local image files with "rb" mode

When using "file" in allowed_direct_url_schemes,
open image files w/ binary mode.

Closes-Bug: #1923313
Change-Id: I52b87d03c49db74002f09cfeea86bc0ac7ce8a42

cinder/image/glance.py

@@ -365,7 +365,7 @@ class GlanceImageService(object):
                     # a system call to cp could have significant performance
                     # advantages, however we do not have the path to files at
                     # this point in the abstraction.
-                    with open(parsed_url.path, "r") as f:
+                    with open(parsed_url.path, "rb") as f:
                         shutil.copyfileobj(f, data)
                     return
 

cinder/tests/unit/image/test_glance.py

@@ -830,6 +830,7 @@ class TestGlanceImageService(test.TestCase):
         self.flags(allowed_direct_url_schemes=['file'])
         self.service.download(self.context, image_id, writer)
         mock_copyfileobj.assert_called_once_with(mock.ANY, writer)
+        mock_open.assert_called_once_with('/tmp/test', 'rb')
 
     @mock.patch('six.moves.builtins.open')
     @mock.patch('shutil.copyfileobj')