$ git clone -n https://src.fedoraproject.org/rpms/botan.git /var/lib/mock/f38-build-side-42-init-devel-851049-28425/root/chroot_tmpdir/scmroot/botan
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-851049-28425/root/chroot_tmpdir/scmroot/botan'...
$ git fetch origin f3877e62a7a67f9dd7552e3b447ebdcf60817e5e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/botan
 * [new ref]         f3877e62a7a67f9dd7552e3b447ebdcf60817e5e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f3877e6 Add patch to fix FTBFS.