diff -r cfb32979abcd -r 8da30ceae88f mercurial/pycompat.py
--- a/mercurial/pycompat.py	Mon Apr 09 12:27:52 2018 -0700
+++ b/mercurial/pycompat.py	Mon Apr 09 12:28:57 2018 -0700
@@ -26,7 +26,10 @@
     import Queue as _queue
     import SocketServer as socketserver
     import xmlrpclib
+
+    from .thirdparty.concurrent import futures
 else:
+    import concurrent.futures as futures
     import http.cookiejar as cookielib
     import http.client as httplib
     import pickle