// But default to turning off ControlMaster.
	if os.Getenv("GIT_SSH") == "" && os.Getenv("GIT_SSH_COMMAND") == "" {
		os.Setenv("GIT_SSH_COMMAND", "ssh -o ControlMaster=no -o BatchMode=yes")
	}

	if os.Getenv("GCM_INTERACTIVE") == "" {
		os.Setenv("GCM_INTERACTIVE", "never")
	}
	if modRoots != nil {
		// modRoot set before Init was called ("go mod init" does this).