$ git clone -n https://src.fedoraproject.org/rpms/rubygems.git /var/lib/mock/f45-build-35451-695/root/chroot_tmpdir/scmroot/rubygems
Cloning into '/var/lib/mock/f45-build-35451-695/root/chroot_tmpdir/scmroot/rubygems'...
$ git fetch origin 301f0688d8e810e15a5965949b297b29f2336604:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygems
 * [new ref]         301f0688d8e810e15a5965949b297b29f2336604 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 301f068 Update to RubyGems 4.0.19