$ git clone -n https://src.fedoraproject.org/rpms/perl-IPC-Signal.git /var/lib/mock/f45-build-24214-602/root/chroot_tmpdir/scmroot/perl-IPC-Signal
Cloning into '/var/lib/mock/f45-build-24214-602/root/chroot_tmpdir/scmroot/perl-IPC-Signal'...
$ git fetch origin 47b1e0e5a65ebcbc5f82585718f260d8fe842d0f:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-IPC-Signal
 * [new ref]         47b1e0e5a65ebcbc5f82585718f260d8fe842d0f -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 47b1e0e Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild