It's used at build time in 8 crates.

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