diff --git a/requirements.txt b/requirements.txt
index fc35b1dd5ec357eadfe2025d9369564437c5eb26..fa9f5fb96816092841bd88e5b03692bb1e7c5663 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -71,9 +71,8 @@ python-memcached
 # }}}
 
 # {{{ A task queue, used to execute long-running tasks
-celery==4.1.0
-# https://github.com/celery/kombu/issues/870
-kombu==4.1.0
+celery==4.2.1
+kombu==4.2.2-post1
 django-celery-results==1.0.1
 
 # }}}
diff --git a/tests/test_calendar.py b/tests/test_calendar.py
index 7d65a6ddcc206c172569105cd9495b84663b486c..70cefc16669796e6ae2df3508c6cd612c7f47279 100644
--- a/tests/test_calendar.py
+++ b/tests/test_calendar.py
@@ -602,7 +602,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
 
         self.addCleanup(factories.EventFactory.reset_sequence)
 
-    def get_course_calender_view(self, course_identifier=None):
+    def get_course_calendar_view(self, course_identifier=None):
         course_identifier = course_identifier or self.get_default_course_identifier()
         return self.c.get(self.get_course_calender_url(course_identifier))
 
@@ -616,12 +616,12 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
                 "course.utils.CoursePageContext.has_permission"
         ) as mock_has_pperm:
             mock_has_pperm.return_value = False
-            resp = self.get_course_calender_view()
+            resp = self.get_course_calendar_view()
             self.assertEqual(resp.status_code, 403)
 
     def test_neither_events_nor_event_file(self):
         self.mock_get_now_or_fake_time.return_value = self.default_faked_now
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
         self.assertEqual(resp.status_code, 200)
         self.assertResponseContextEqual(resp, "events_json", '[]')
         self.assertResponseContextEqual(resp, "event_info_list", [])
@@ -636,7 +636,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
             kind=self.default_event_kind, course=self.course,
             time=self.default_event_time + timedelta(hours=1))
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
         self.assertEqual(resp.status_code, 200)
 
         events_json = json.loads(resp.context["events_json"])
@@ -664,7 +664,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
             shown_in_calendar=False,
             time=self.default_event_time + timedelta(hours=1))
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
         self.assertEqual(resp.status_code, 200)
 
         events_json = json.loads(resp.context["events_json"])
@@ -681,7 +681,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
             kind=self.default_event_kind, course=self.course,
             time=self.default_event_time,
             end_time=self.default_event_time + timedelta(hours=1))
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
         self.assertEqual(resp.status_code, 200)
 
         events_json = json.loads(resp.context["events_json"])
@@ -702,7 +702,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
         self.course.end_date = (self.default_faked_now - timedelta(weeks=1)).date()
         self.course.save()
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
         self.assertEqual(resp.status_code, 200)
 
         self.assertResponseContextEqual(resp, "events_json", '[]')
@@ -715,7 +715,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
         self.course.end_date = (self.default_faked_now + timedelta(weeks=1)).date()
         self.course.save()
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
         self.assertEqual(resp.status_code, 200)
 
         self.assertResponseContextEqual(resp, "events_json", '[]')
@@ -727,13 +727,15 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
         # make sure it works
         self.switch_to_fake_commit_sha()
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
 
         self.assertResponseContextEqual(resp, "events_json", '[]')
         self.assertResponseContextEqual(resp, "event_info_list", [])
 
     def test_events_file_with_events_test1(self):
         self.switch_to_fake_commit_sha()
+        self.mock_get_now_or_fake_time.return_value = (
+                self.default_event_time - timedelta(days=5))
 
         # lecture 1
         lecture1_start_time = self.default_event_time - timedelta(weeks=1)
@@ -746,7 +748,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
             kind=self.default_event_kind, course=self.course,
             time=self.default_event_time, ordinal=2)
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
 
         events_json = json.loads(resp.context["events_json"])
         self.assertEqual(len(events_json), 2)
@@ -810,7 +812,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
             time=test_start_time,
             ordinal=None)
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
 
         events_json = json.loads(resp.context["events_json"])
         self.assertEqual(len(events_json), 3)
@@ -858,7 +860,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
                 lecture3_start_time + timedelta(minutes=5))
 
         # no EventInfo object
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
         self.assertResponseContextEqual(resp, "event_info_list", [])
 
     def test_events_file_with_events_test3(self):
@@ -871,7 +873,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
             time=self.default_event_time,
             end_time=exam_end_time)
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
 
         events_json = json.loads(resp.context["events_json"])
         self.assertEqual(len(events_json), 1)
@@ -907,7 +909,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
             kind=self.default_event_kind, course=self.course,
             time=lecture3_start_time, ordinal=3)
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
 
         events_json = json.loads(resp.context["events_json"])
         self.assertEqual(len(events_json), 2)
@@ -924,7 +926,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
         lecture2_evt.end_time = lecture2_end_time
         lecture2_evt.save()
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
 
         events_json = json.loads(resp.context["events_json"])
         self.assertEqual(len(events_json), 2)
@@ -949,7 +951,7 @@ class ViewCalendarTest(SingleCourseTestMixin, HackRepoMixin, TestCase):
 
             lecture2_end_time += timedelta(hours=1)
 
-        resp = self.get_course_calender_view()
+        resp = self.get_course_calendar_view()
 
         events_json = json.loads(resp.context["events_json"])
         self.assertEqual(len(events_json), 2)
diff --git a/tests/test_versioning.py b/tests/test_versioning.py
index 9856709bc171d5e019c9643d445d0592d6674572..dd964241860131f18f66151b436aef6a5cc3e8e3 100644
--- a/tests/test_versioning.py
+++ b/tests/test_versioning.py
@@ -288,7 +288,12 @@ class ParamikoSSHVendorTest(unittest.TestCase):
     def test_invalid(self):
         from paramiko.ssh_exception import AuthenticationException
 
-        expected_error_msg = "Authentication failed"
+        expected_error_msgs = [
+                "Authentication failed",
+
+                # Raised when run in a user account that has
+                # an (encrypted) key file in $HOME/.ssh.
+                "Private key file is encrypted"]
         with self.assertRaises(AuthenticationException) as cm:
             # This is also used to ensure paramiko.client.MissingHostKeyPolicy
             # is added to the client
@@ -297,7 +302,8 @@ class ParamikoSSHVendorTest(unittest.TestCase):
                 command="git-upload-pack '/bar/baz'",
                 username=None,
                 port=None)
-        self.assertIn(expected_error_msg, str(cm.exception))
+        self.assertTrue(any(
+            msg in str(cm.exception) for msg in expected_error_msgs))
 
         with self.assertRaises(AuthenticationException) as cm:
             self.ssh_vendor.run_command(
@@ -305,7 +311,8 @@ class ParamikoSSHVendorTest(unittest.TestCase):
                 command="git-upload-pack '/bar/baz'",
                 username="me",
                 port=22)
-        self.assertIn(expected_error_msg, str(cm.exception))
+        self.assertTrue(any(
+            msg in str(cm.exception) for msg in expected_error_msgs))
 
         expected_error_msg = "Bad authentication type"
 
@@ -985,7 +992,7 @@ class GetCommitMessageAsHtmlTest(VersioningRepoMixin, SingleCourseTestMixin,
         repo_dict = {
             commit_sha_1: FakeCommit("a_commit", message=b"test a > b  "),
             commit_sha_2: FakeCommit("another_commit", message=b"  <p>test</p>"),
-            commit_sha_3: FakeCommit("another_commit", message=b"abc\uDC80"),
+            commit_sha_3: FakeCommit("another_commit", message=b"abc\\uDC80"),
         }
         repo = mock.MagicMock()
         repo.__getitem__.side_effect = repo_dict.__getitem__