[BUG] Decryption fails if message was signed with an unknown key

[Simon Hirscher]

Dear notmuch developers,

This is now the second time the following has happened to me:

#########
$ notmuch show --decrypt id:xyz at example.com

message{ id:xyz at example.com depth:0 match:1 excluded:0 filename:/home/simon/***

header{
John Doe <sender at example.com> (Today 21:52) (encrypted inbox new)
Subject: foobar
From: John Doe <sender at example.com>
To: ***
Date: Thu, 01 Jan 1970 00:00:00 +0000

header}

body{
Failed to decrypt part: gpg: ASCII-Hülle: Version: GnuPG v2.0.17 (MingW32)
gpg: <list of keys the message was encrypted with>
gpg: AES256 encrypted data
gpg: Original file name=''
gpg: Signature from Thu 01 Jan 1970 00:00:00 UTC by DSA key ID <sender's key>
gpg: Signature cannot be verified. Public key not found

part{ ID: 1, Content-type: multipart/encrypted

part{ ID: 2, Content-type: application/pgp-encrypted
Non-text part: application/pgp-encrypted

part}

part{ ID: 3, Filename: encrypted.asc, Content-type: application/octet-stream
Non-text part: application/octet-stream

part}

part}

body}

message}

$ gpg --recv-keys <sender's key>

$ notmuch show --decrypt id:xyz at example.com

[…]
Hey there,
Now the decryption worked!
[…]

############

Also, I should add that manually decrypting the message with gpg (i.e.
without using notmuch) already worked *before* I added the sender's
key (not shown above). Still, notmuch obviously doesn't like it when
the sender is unknown.

I hope you're going to look into this. Thank you!