--- a/mercurial/util.py Tue Aug 01 10:14:25 2017 -0400
+++ b/mercurial/util.py Thu Jul 20 01:30:41 2017 -0700
@@ -602,6 +602,10 @@
finally:
tr.release()
+@contextlib.contextmanager
+def nullcontextmanager():
+ yield
+
class _lrucachenode(object):
"""A node in a doubly linked list.