Merge ~cjwatson/launchpad:fix-py3only-unittest-mock into launchpad:master

[Colin Watson]

Fix a couple of stray uses of mock

Fixes test regression from https://code.launchpad.net/~cjwatson/launchpad/+git/launchpad/+merge/406943.

[Colin Watson (cjwatson)]

Self-approving a trivial test fix.

review: Approve

diff --git a/lib/lp/archivepublisher/tests/test_signing.py b/lib/lp/archivepublisher/tests/test_signing.py
index 505b937..95e314a 100644
--- a/lib/lp/archivepublisher/tests/test_signing.py
+++ b/lib/lp/archivepublisher/tests/test_signing.py
@@ -11,12 +11,12 @@ import re
 import shutil
 import stat
 import tarfile
+from unittest.mock import call
 
 from fixtures import (
     MockPatch,
     MonkeyPatch,
     )
-from mock import call
 from pytz import utc
 import scandir
 import six
diff --git a/lib/lp/services/librarianserver/tests/test_swift.py b/lib/lp/services/librarianserver/tests/test_swift.py
index f3513e7..d38207b 100644
--- a/lib/lp/services/librarianserver/tests/test_swift.py
+++ b/lib/lp/services/librarianserver/tests/test_swift.py
@@ -9,8 +9,8 @@ import hashlib
 import io
 import os.path
 import time
+from unittest.mock import patch
 
-from mock import patch
 import six
 from swiftclient import client as swiftclient
 import transaction