$ git clone -n https://src.fedoraproject.org/rpms/rust-git2.git /var/lib/mock/f41-build-side-1-3006365-36745/root/chroot_tmpdir/scmroot/rust-git2
Cloning into '/var/lib/mock/f41-build-side-1-3006365-36745/root/chroot_tmpdir/scmroot/rust-git2'...
$ git fetch origin e226ffb8ab4d8bb9a5d388dcb6d0e3c27871827e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rust-git2
 * [new ref]         e226ffb8ab4d8bb9a5d388dcb6d0e3c27871827e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e226ffb Drop dependency on time ^0.1 which is only required for building examples