[CentOS] CentOS 7 and systemd: SysV initscript: how detect boot vs. interactive use?

Moving from CentOS 5 to CentOS 7, discovered that a test in a SysV
initscript for whether it is running interactively, instead of at boot
time, no longer works.

Under CentOS 7 / systemd, is there some way for the initscript to know
this?