diff -ru pytz-2018.4.orig/pytz/lazy.py pytz-2018.4/pytz/lazy.py
--- pytz-2018.4.orig/pytz/lazy.py	2018-04-24 15:47:46.293980100 -0400
+++ pytz-2018.4/pytz/lazy.py	2018-04-24 15:56:06.281648286 -0400
@@ -1,4 +1,7 @@
-from threading import RLock
+try:
+    from threading import RLock
+except (ImportError, ModuleNotFoundError):
+    from dummy_threading import RLock
 try:
     from collections.abc import Mapping as DictMixin
 except ImportError:  # Python < 3.3
Binary files pytz-2018.4.orig/pytz/__pycache__/lazy.cpython-36.pyc and pytz-2018.4/pytz/__pycache__/lazy.cpython-36.pyc differ