$ git clone -n https://src.fedoraproject.org/rpms/perl-Gtk2-Ex-CalendarButton.git /var/lib/mock/f45-build-23831-599/root/chroot_tmpdir/scmroot/perl-Gtk2-Ex-CalendarButton
Cloning into '/var/lib/mock/f45-build-23831-599/root/chroot_tmpdir/scmroot/perl-Gtk2-Ex-CalendarButton'...
$ git fetch origin a6a7145315f67c375a5f89904555e1156b3ddade:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/perl-Gtk2-Ex-CalendarButton
 * [new ref]         a6a7145315f67c375a5f89904555e1156b3ddade -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at a6a7145 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild