where is the backup su stored by Voodoo OTA RootKeeper?

When you make a backup of su in Voodoo OTA RootKeeper 2.0.3 on Android 4.1.2 where does it go?
/system/usr/we-need-root/su-backup

I took a statically-linked version of an su which literally just changes the uid to 0 when its run setuid and stuck it there too, named unrestricted-su (it doesn't linkup with SuperSU for privilege prompts or anything).

Note this only works on Android < 4.2 since 4.3 mounts /system setuid and does not allow dalvik zygotes to run setuid binaries.