$ git clone -n https://src.fedoraproject.org/rpms/folly.git /var/lib/mock/f41-build-814759-149160/root/chroot_tmpdir/scmroot/folly
Cloning into '/var/lib/mock/f41-build-814759-149160/root/chroot_tmpdir/scmroot/folly'...
$ git fetch origin 440f075002b1ce085bc203d82b30c03b6e5752e3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/folly
 * [new ref]         440f075002b1ce085bc203d82b30c03b6e5752e3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 440f075 Add riscv64 support.