Timezones now always requires pytz

celery/utils/timeutils.py

@@ -17,12 +17,14 @@ from datetime import datetime, timedelta
 from dateutil import tz
 from dateutil.parser import parse as parse_iso8601
 
+from celery.exceptions import ImproperlyConfigured
+
 from .text import pluralize
 
 try:
     import pytz
-except ImportError:
-    pytz = None  # noqa
+except ImportError:     # pragma: no cover
+    pytz = None         # noqa
 
 
 DAYNAMES = "sun", "mon", "tue", "wed", "thu", "fri", "sat"
@@ -41,15 +43,6 @@ TIME_UNITS = (("day", 60 * 60 * 24.0, lambda n: "%.2f" % n),
               ("second", 1.0, lambda n: "%.2f" % n))
 
 
-class UnknownTimezone(Exception):
-    """No specification exists for the timezone specified.  Consider
-    installing the pytz library to get access to more timezones."""
-
-
-def _is_naive(dt):
-    return bool(dt.tzinfo)
-
-
 class _Zone(object):
 
     def tz_or_local(self, tzinfo=None):
@@ -63,12 +56,12 @@ class _Zone(object):
 
     def get_timezone(self, zone):
         if isinstance(zone, basestring):
-            if pytz:
-                return pytz.timezone(zone)
-            zone = tz.gettz(zone)
-            if zone is None:
-                raise UnknownTimezone(UnknownTimezone.__doc__)
-            return zone
+            if pytz is None:
+                if zone == "UTC":
+                    return tz.gettz("UTC")
+                raise ImproperlyConfigured(
+                    "Timezones requires the pytz library")
+            return pytz.timezone(zone)
         return zone
 
     @cached_property