$ git clone -n https://src.fedoraproject.org/rpms/perl-Test-Block.git /var/lib/mock/f45-build-26588-618/root/chroot_tmpdir/scmroot/perl-Test-Block
Cloning into '/var/lib/mock/f45-build-26588-618/root/chroot_tmpdir/scmroot/perl-Test-Block'...
$ git fetch origin 5b6de5cfc0f3ec6d69e6071ed9d97f0fead08fc9:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Test-Block
 * [new ref]         5b6de5cfc0f3ec6d69e6071ed9d97f0fead08fc9 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5b6de5c Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild