$ git clone -n https://src.fedoraproject.org/rpms/perl-Math-Vec.git /var/lib/mock/f45-build-24871-606/root/chroot_tmpdir/scmroot/perl-Math-Vec
Cloning into '/var/lib/mock/f45-build-24871-606/root/chroot_tmpdir/scmroot/perl-Math-Vec'...
$ git fetch origin 769eb47b088f55f0a6cf120473fdb5dd8e316101:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Math-Vec
 * [new ref]         769eb47b088f55f0a6cf120473fdb5dd8e316101 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 769eb47 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild