$ git clone -n https://src.fedoraproject.org/rpms/perl-File-Which.git /var/lib/mock/f45-build-23622-598/root/chroot_tmpdir/scmroot/perl-File-Which
Cloning into '/var/lib/mock/f45-build-23622-598/root/chroot_tmpdir/scmroot/perl-File-Which'...
$ git fetch origin f9bdbe3c9b053c522370342325720799f94be9b0:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-File-Which
 * [new ref]         f9bdbe3c9b053c522370342325720799f94be9b0 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f9bdbe3 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild