Fix os.path.sep replacement on Windows.

dulwich/refs.py

@@ -489,7 +489,8 @@ class DiskRefsContainer(RefsContainer):
         for root, unused_dirs, files in os.walk(path):
             dir = root[len(path):]
             if os.path.sep != '/':
-                dir = dir.replace(os.path.sep, "/")
+                dir = dir.replace(os.path.sep.encode(
+                    sys.getfilesystemencoding()), b"/")
             dir = dir.strip(b'/')
             for filename in files:
                 refname = b"/".join(([dir] if dir else []) + [filename])
@@ -511,7 +512,8 @@ class DiskRefsContainer(RefsContainer):
         for root, unused_dirs, files in os.walk(refspath):
             dir = root[len(path):]
             if os.path.sep != '/':
-                dir = dir.strip(os.path.sep).replace(os.path.sep, "/")
+                dir = dir.replace(
+                    os.path.sep.encode(sys.getfilesystemencoding()), b"/")
             for filename in files:
                 refname = b"/".join([dir, filename])
                 if check_ref_format(refname):