$ git clone -n https://src.fedoraproject.org/rpms/rubygem-rmail.git /var/lib/mock/f45-build-35236-694/root/chroot_tmpdir/scmroot/rubygem-rmail
Cloning into '/var/lib/mock/f45-build-35236-694/root/chroot_tmpdir/scmroot/rubygem-rmail'...
$ git fetch origin 5f433599454644166f44c2c8880900d617a3a374:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-rmail
 * [new ref]         5f433599454644166f44c2c8880900d617a3a374 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 5f43359 Rebuilt for https://fedoraproject.org/wiki/Fedora_45_Mass_Rebuild