Fix test failing on unix

Author: Andrej730

test/test_index.py

@@ -1189,7 +1189,7 @@ def test_index_add_non_normalized_path(self, rw_repo):
         file.touch()
         non_normalized_path = file.as_posix()
         if os.name != "nt":
-            non_normalized_path = non_normalized_path.replace("/", "\\")
+            non_normalized_path = "/" + non_normalized_path[1:].replace("/", "//")
 
         rw_repo.index.add(non_normalized_path)