$ git clone -n https://src.fedoraproject.org/rpms/rubygem-prawn.git /var/lib/mock/f45-build-35152-693/root/chroot_tmpdir/scmroot/rubygem-prawn
Cloning into '/var/lib/mock/f45-build-35152-693/root/chroot_tmpdir/scmroot/rubygem-prawn'...
$ git fetch origin b9d8f7770bdaf8f5829504664ea345a2e65e45df:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-prawn
 * [new ref]         b9d8f7770bdaf8f5829504664ea345a2e65e45df -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b9d8f77 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild