RecyclerView pre-rendering causes threaded messages to be marked as read
See https://code.briarproject.org/akwizgran/briar/merge_requests/818#note_27170:
The latest versions of the support library use a performance optimization for
RecyclerView
which pre-renders list items on spare UiThread cycles. This callsonBindViewHolder()
which we currently use to determine whether a user has seen a post.