$ git clone -n https://src.fedoraproject.org/rpms/R-websocket.git /var/lib/mock/f38-build-720831-97932/root/chroot_tmpdir/scmroot/R-websocket
Cloning into '/var/lib/mock/f38-build-720831-97932/root/chroot_tmpdir/scmroot/R-websocket'...
$ git fetch origin eec79a7e0a2bc4788b2bc30efc14de54e1cc87a3:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/R-websocket
 * [new ref]         eec79a7e0a2bc4788b2bc30efc14de54e1cc87a3 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at eec79a7 Ignore vignettes