$ git clone -n https://src.fedoraproject.org/rpms/plasma-oxygen.git /var/lib/mock/f40-build-799335-142260/root/chroot_tmpdir/scmroot/plasma-oxygen
Cloning into '/var/lib/mock/f40-build-799335-142260/root/chroot_tmpdir/scmroot/plasma-oxygen'...
$ git fetch origin b6ae91b485f2b1344c29e57970cb2670a7bf4206:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/plasma-oxygen
 * [new ref]         b6ae91b485f2b1344c29e57970cb2670a7bf4206 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b6ae91b 6.0.2