for git_var in $(set | awk -F= '/^GIT_/ {print $1}')
do
    unset -v "$git_var"
done
export GIT_CONFIG_NOSYSTEM=true
export GIT_CONFIG_GLOBAL=/dev/null
export GIT_AUTHOR_NAME="A U Thor"
export GIT_AUTHOR_EMAIL="author@domain.tld"
export GIT_COMMITTER_NAME="C O Mitter"
export GIT_COMMITTER_EMAIL="committer@domain.tld"
export GIT_AUTHOR_DATE="1500000000 -0500"
export GIT_COMMITTER_DATE="1500000000 -0500"
export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main # Suppress noisy warning.