git hook to ensure commit doesn't break rustfmt

pre-commit

#!/bin/sh

# Put in your Rust repository's .git/hooks/pre-commit to ensure you never
# breaks rustfmt.                                                                                                                      
#
# WARNING: rustfmt is a fast moving target so ensure you have the version that
#          all contributors have.

for FILE in `git diff --cached --name-only`; do
    #if [[ $FILE == *.rs ]] && ! rustup run nightly rustfmt --write-mode diff --skip-children $FILE; then
    if [[ $FILE == *.rs ]] && ! rustfmt --write-mode diff --skip-children $FILE; then
        echo "Commit rejected due to invalid formatting of \"$FILE\" file."

        exit 1
    fi
done