[BUG] Notmuch keeps adding notmuch-address-expand-name to message-completion-alist

[Attic Hermit]

When I invocate compose-mail or something related with the message-mode
buffer and Notmuch, Notmuch keeps adding a pair like below to
`message-completion-alist`:

  ("^\\(Resent-\\)?\\(To\\|B?Cc\\|Reply-To\\|From\\|Mail-Followup-To\\|Mail-Copies-To\\):"
  . notmuch-address-expand-name)

I think there's bug in `notmuch-address-setup` on `notmuch-address.el`.
It checks that the pair exists in the `message-completion-alist` by
`memq`, but it seems to be amended to `member` instead.

P.S. Because I'm not a programming expert or a student, I don't know how
to send a patch to amend this problem. So I send where the bug was found
and the way how I tinkered it in English. I searched the file where bug
exists in the git repository of Notmuch, and found that there still was
a bug. I hope this will help to fix the bug.
-- 
Attic Hermit