$ git clone -n https://src.fedoraproject.org/rpms/rubygem-gdk4.git /var/lib/mock/f42-build-side-1-3501714-45976/root/chroot_tmpdir/scmroot/rubygem-gdk4
Cloning into '/var/lib/mock/f42-build-side-1-3501714-45976/root/chroot_tmpdir/scmroot/rubygem-gdk4'...
$ git fetch origin d562a6154c28384243b405b9c2766ccb4f16eae8:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/rubygem-gdk4
 * [new ref]         d562a6154c28384243b405b9c2766ccb4f16eae8 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at d562a61 4.2.9 entry