[#1635] Handle "1 day" in string_to_timedelta()

Handle strings like "1 day" or "1 day, 3:23:46" etc. in the
string_to_timedelta() function used to parse the
ckan.email_notifications_since config setting.

ckan/lib/email_notifications.py

@@ -34,7 +34,7 @@ def string_to_timedelta(s):
 
     '''
     patterns = []
-    days_only_pattern = '(?P<days>\d+) days'
+    days_only_pattern = '(?P<days>\d+) day(s)?'
     patterns.append(days_only_pattern)
     hms_only_pattern = '(?P<hours>\d?\d):(?P<minutes>\d\d):(?P<seconds>\d\d)'
     patterns.append(hms_only_pattern)

ckan/tests/lib/test_email_notifications.py

@@ -11,6 +11,8 @@
 
 
 def test_string_to_time_delta():
+    assert email_notifications.string_to_timedelta('1 day') == (
+            datetime.timedelta(days=1))
     assert email_notifications.string_to_timedelta('2 days') == (
             datetime.timedelta(days=2))
     assert email_notifications.string_to_timedelta('14 days') == (
@@ -20,6 +22,8 @@ def test_string_to_time_delta():
     assert email_notifications.string_to_timedelta('4:35:12.087465') == (
             datetime.timedelta(hours=4, minutes=35, seconds=12,
                 milliseconds=87, microseconds=465))
+    assert email_notifications.string_to_timedelta('1 day, 3:23:34') == (
+            datetime.timedelta(days=1, hours=3, minutes=23, seconds=34))
     assert email_notifications.string_to_timedelta('7 days, 3:23:34') == (
             datetime.timedelta(days=7, hours=3, minutes=23, seconds=34))
     assert email_notifications.string_to_timedelta(