When the 'cmdline' is the last entry in 'rs->history' array, there is
no need to put this entry to the end of the array, partly because it is
the last entry, and partly because the next operition will lead to array
index out of bounds.

Reported-by: Euler Robot <euler.robot@huawei.com>
Signed-off-by: Alex Chen <alex.chen@huawei.com>
Message-id: 20201203135043.117072-1-alex.chen@huawei.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>