It's used at build time in 9 crates (8 directly).

Depender (with downloads and own rev deps) grev version
goggled build ^0.1.3
1 tetromino build ^0.1.3
blazecli build ^0.1.3
btrfs-backup build ^0.1.3
notnow build ^0.1.3
chroot-deploy build ^0.1.3
apcacli build ^0.1.3
mail-message build ^0.1.3