emacs: Wrong "From" address when forwarding a mail

[Jinwoo Lee]

I have two accounts set up in my notmuch configuration.  And when I'm
forwarding a mail using notmuch-show-forward-message, it always uses my
primary account as its From address no matter which account that
original mail has been delivered to.

For example:
1. I got a mail delivered to my personal address, personal at somemail.com,
   which is my secondary account.
2. I want to forward the mail to someone else and I press 'f' for
   notmuch-show-forward-message.
3. It always uses my corp address, corp at somecompany.com, which is my
   primary account, as the From address, instead of
   personal at somemail.com.

This is quite annoying and has some privacy issues because my corporate
account may be scanned by my employer.  I'm working around this by doing
'C-u f', which allows me to choose the From address, but it's very easy
to just press 'f' and make a mistake.

Can we make notmuch-show-forward-message behave like
notmuch-show-reply-sender, which chooses the From address correctly?

Thanks,
-jinwoo