Renaming (git mv) a directory shows the files as deleted at the source, but not the directories

1. Cloned the rails repository.
2. mkdir source
3. git mv all the top level directories to source
4. get commit shows the files as renamed

   ...
    rename {railties => source/railties}/test/generators/generator_generator_test.rb (100%)
    rename {railties => source/railties}/test/generators/generators_test_helper.rb (100%)
   

5. Scan the repo with the rename detection as "renames"
6. The top level directories aren't shown as greyed out
   

Expected that the directories would be shown as greyed out since they no longer exist in the repo: