$ git clone -n https://src.fedoraproject.org/rpms/build2.git /var/lib/mock/f38-build-side-42-init-devel-613416-26295/root/chroot_tmpdir/scmroot/build2
Cloning into '/var/lib/mock/f38-build-side-42-init-devel-613416-26295/root/chroot_tmpdir/scmroot/build2'...
$ git fetch origin f4dcd9e071cda766f99103dd1f26a058cb9e8f00:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/build2
 * [new ref]         f4dcd9e071cda766f99103dd1f26a058cb9e8f00 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f4dcd9e Re-enable C++ modules tests on PPC64LE