$ git clone -n https://src.fedoraproject.org/rpms/erlang-cowlib.git /var/lib/mock/f41-build-1322170-23525/root/chroot_tmpdir/scmroot/erlang-cowlib
Cloning into '/var/lib/mock/f41-build-1322170-23525/root/chroot_tmpdir/scmroot/erlang-cowlib'...
$ git fetch origin 0597f5d8ea1555cf9b597bf276ebbb18d26b1c96:KOJI_FETCH_HEAD
From https://src.fedoraproject.org/rpms/erlang-cowlib
 * [new ref]         0597f5d8ea1555cf9b597bf276ebbb18d26b1c96 -> KOJI_FETCH_HEAD
$ git reset --hard KOJI_FETCH_HEAD
HEAD is now at 0597f5d Remove old source