diff -ru python-dateutil-2.7.2.orig/dateutil/tz/tz.py python-dateutil-2.7.2/dateutil/tz/tz.py
--- python-dateutil-2.8.1/dateutil/tz/tz.py.orig 2019-11-24 17:23:10.395546087 -0500
+++ python-dateutil-2.8.1/dateutil/tz/tz.py  2019-11-24 17:24:06.125760830 -0500
@@ -18,7 +18,6 @@

 import six
 from six import string_types
-from six.moves import _thread
 from ._common import tzname_in_python2, _tzinfo
 from ._common import tzrangebase, enfold
 from ._common import _validate_fromutc_inputs
@@ -38,6 +37,14 @@
 EPOCHORDINAL = EPOCH.toordinal()


+class _dummy_lock:
+    def __enter__(self, *args, **kwargs):
+        pass
+
+    def __exit__(self, *args, **kwargs):
+        pass
+
+
 @six.add_metaclass(_TzSingleton)
 class tzutc(datetime.tzinfo):
     """
@@ -1172,7 +1179,7 @@
         self._comps = comps
         self._cachedate = []
         self._cachecomp = []
-        self._cache_lock = _thread.allocate_lock()
+        self._cache_lock = _dummy_lock()

     def _find_comp(self, dt):
         if len(self._comps) == 1:
@@ -1547,7 +1554,7 @@
             self.__instances = weakref.WeakValueDictionary()
             self.__strong_cache_size = 8
             self.__strong_cache = OrderedDict()
-            self._cache_lock = _thread.allocate_lock()
+            self._cache_lock = _dummy_lock()

         def __call__(self, name=None):
             with self._cache_lock:

diff -ur python-dateutil-2.7.2/dateutil/rrule.py python-dateutil-2.7.2.bak/dateutil/rrule.py
--- python-dateutil-2.7.2/dateutil/rrule.py	2018-03-24 11:53:31.000000000 -0400
+++ python-dateutil-2.7.2.bak/dateutil/rrule.py	2018-05-17 09:36:33.295290743 -0400
@@ -17,7 +17,20 @@
     from fractions import gcd

 from six import advance_iterator, integer_types
-from six.moves import _thread, range
+try:
+    from six.moves._thread import allocate_lock
+except ModuleNotFoundError:
+    class allocate_lock:
+       def locked(self):
+           return False
+
+       def release(self):
+           pass
+
+       def acquire(self):
+           pass
+
+from six.moves import range
 import heapq

 from ._common import weekday as weekdaybase
@@ -94,7 +107,7 @@
     def __init__(self, cache=False):
         if cache:
             self._cache = []
-            self._cache_lock = _thread.allocate_lock()
+            self._cache_lock = allocate_lock()
             self._invalidate_cache()
         else:
             self._cache = None