$ git clone -n https://src.fedoraproject.org/rpms/R-websocket.git /var/lib/mock/f41-build-821097-152412/root/chroot_tmpdir/scmroot/R-websocket
Cloning into '/var/lib/mock/f41-build-821097-152412/root/chroot_tmpdir/scmroot/R-websocket'...
$ git fetch origin b689ede3126239f4957ecccd27fc5f48387b5021:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-websocket
 * [new ref]         b689ede3126239f4957ecccd27fc5f48387b5021 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at b689ede R-maint-sig mass rebuild