Clean git submodules

clean-git-submodules.sh

#!/bin/bash

# Context: you have a number of git submodules and those git repositories
# are now dirty with build artifacts.  To completely clean the submodules
# and reset them to their original clone state, perform the following:

git submodule foreach 'git fetch origin; git checkout $(git rev-parse --abbrev-ref HEAD); git reset --hard origin/$(git rev-parse --abbrev-ref HEAD); git submodule update --recursive; git clean -dfx'