On Windows, removing a directory recursively with `cmake -E remove_directory` or `file(REMOVE_RECURSE)` occasionally fails for a few reasons: * Races with anti-virus tools locking recently created files. * Races with other tools creating new entries in a directory. * Races between removing all entries in a directory and removing the directory itself. NTFS deletion is not synchronous. Our implementation currently uses KWSys [`SystemTools::RemoveADirectory`](https://gitlab.kitware.com/cmake/cmake/blob/v3.15.2/Source/kwsys/SystemTools.cxx#L2755). It could be improved with a more robust removal approach. Meanwhile some code paths are using [`cmSystemTools::RepeatedRemoveDirectory`](https://gitlab.kitware.com/cmake/cmake/blob/v3.15.2/Source/cmSystemTools.cxx#L2952) to work around this.