No url found for submodule path 'courses/dl2/imdb_scripts/wikiextractor' in .gitmodules

Trying to clone fastai source code from https://github.com/fastai/fastai and I get this error:

No url found for submodule path ‘courses/dl2/imdb_scripts/wikiextractor’ in .gitmodules

Is there a dependency I need first or what? I have the latest git installation (2.21.0 for Windows, 64 bit).

FIXED: just use git bash to do the clone instead of the Git GUI tool. No idea why Git GUI didn’t work on the clone- never failed me before.