Angular style commit message <type> tagging completion (https://gist.github.com/stephenparish/9941e89d80e2bc58a153) added atop https://github.com/robbyrussell/oh-my-zsh/blob/d848c94804918138375041a9f800f401bec12068/plugins/gitfast/git-completion.bash#L1101-L1144

_git_commit

_git_commit ()
{
	case "$prev" in
	(-c | -C) __gitcomp_nl "$(__git_refs)" "" "${cur}"
		return ;;
	(-m) __gitcomp "feat: fix: docs: style: refactor: test: chore:
		" "" "${cur}"
		return
		;;
	esac
	case "$cur" in
	(--message=*) __gitcomp "feat: fix: docs: style: refactor: test: chore:
		" "" "${cur##--message=}"
		return
		;;
	--cleanup=*)
		__gitcomp "default scissors strip verbatim whitespace
			" "" "${cur##--cleanup=}"
		return
		;;
	--reuse-message=*|--reedit-message=*|\
	--fixup=*|--squash=*)
		__gitcomp_nl "$(__git_refs)" "" "${cur#*=}"
		return
		;;
	--untracked-files=*)
		__gitcomp "all no normal" "" "${cur##--untracked-files=}"
		return
		;;
	--*)
		__gitcomp "
			--all --author= --signoff --verify --no-verify
			--edit --no-edit
			--amend --include --only --interactive
			--dry-run --reuse-message= --reedit-message=
			--reset-author --file= --message= --template=
			--cleanup= --untracked-files --untracked-files=
			--verbose --quiet --fixup= --squash=
			"
		return
	esac

	if git rev-parse --verify --quiet HEAD >/dev/null; then
		__git_complete_index_file "--committable"
	else
		# This is the first commit
		__git_complete_index_file "--cached"
	fi
}