$ git clone -n https://src.fedoraproject.org/rpms/mailnag.git /var/lib/mock/f45-build-17966-506/root/chroot_tmpdir/scmroot/mailnag
Cloning into '/var/lib/mock/f45-build-17966-506/root/chroot_tmpdir/scmroot/mailnag'...
$ git fetch origin e993151515a3a94bb99d6fede34fafe57fc8ee46:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/mailnag
 * [new ref]         e993151515a3a94bb99d6fede34fafe57fc8ee46 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at e993151 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild