$ git clone -n https://src.fedoraproject.org/rpms/R-rJava.git /var/lib/mock/f40-build-1824193-24918/root/chroot_tmpdir/scmroot/R-rJava
Cloning into '/var/lib/mock/f40-build-1824193-24918/root/chroot_tmpdir/scmroot/R-rJava'...
$ git fetch origin f53c030a6f32fd4c25c09d75896025b57b77c501:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-rJava
 * [new ref]         f53c030a6f32fd4c25c09d75896025b57b77c501 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f53c030 Merge branch 'rawhide' into f40