$ git clone -n https://src.fedoraproject.org/rpms/rust-generic-array0.12.git /var/lib/mock/f45-build-41838-786/root/chroot_tmpdir/scmroot/rust-generic-array0.12
Cloning into '/var/lib/mock/f45-build-41838-786/root/chroot_tmpdir/scmroot/rust-generic-array0.12'...
$ git fetch origin 9851f546d2b3c7f3a58189329c75cd06fee8e384:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-generic-array0.12
 * [new ref]         9851f546d2b3c7f3a58189329c75cd06fee8e384 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 9851f54 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild