Re: [PATCHv2 1/2] submodule init: fail gracefully with a missing .gitmodules file

Stefan Beller [off-list ref] writes:

When there is no .gitmodules file availabe to initialize a submodule
from, `submodule_from_path` just returns NULL. We need to check for
that and abort gracefully. When `submodule init` was implemented in shell,
a missing .gitmodules file would result in an error message

    No url found for submodule path '%s' in .gitmodules

Replicate that error message for now.

Good to start from a faithful conversion.  Thanks for adding a test,
too.

Will queue.