$ git clone -n https://src.fedoraproject.org/rpms/tin.git /var/lib/mock/f45-build-37119-711/root/chroot_tmpdir/scmroot/tin
Cloning into '/var/lib/mock/f45-build-37119-711/root/chroot_tmpdir/scmroot/tin'...
$ git fetch origin 52db63c77c915d4487bb155cfcf02c172becf6eb:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/tin
 * [new ref]         52db63c77c915d4487bb155cfcf02c172becf6eb -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 52db63c update to 2.6.6 (resolves rhbz#2521568)