bpo-39590: make deque.__contains__ and deque.count hold strong references (GH-18421) (GH-18423)

(cherry picked from commit c6dedde160a9fce5d049e860f586ad8f93aec822)

Co-authored-by: sweeneyde <36520290+sweeneyde@users.noreply.github.com>

Co-authored-by: sweeneyde <36520290+sweeneyde@users.noreply.github.com>
3 files changed