$ git clone -n https://src.fedoraproject.org/rpms/plasma-oxygen.git /var/lib/mock/f42-build-side-1-3566282-46733/root/chroot_tmpdir/scmroot/plasma-oxygen
Cloning into '/var/lib/mock/f42-build-side-1-3566282-46733/root/chroot_tmpdir/scmroot/plasma-oxygen'...
$ git fetch origin f2c6db5986d695e3a7373f3cbca66f9714def41e:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/plasma-oxygen
 * [new ref]         f2c6db5986d695e3a7373f3cbca66f9714def41e -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at f2c6db5 6.4.0