As of Gerrit 2.13 we get an error if we vote on a change that has been
merged. As the votes couldn't be before, nor now, changed after Gerrit
submission has been merged (closed) there is no point in voting.
Change-Id: I267cc0db3ca8515056bd0c428ffbdbc7879509c1 Signed-off-by: Andrew Grimberg <agrimberg@linuxfoundation.org>