Fixes issue 10120 (concurrent.futures module is not installed properly), patch by Neil Muller
diff --git a/Makefile.pre.in b/Makefile.pre.in
index b66313b..475d272 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -880,7 +880,7 @@
tkinter/test/test_ttk site-packages test \
test/decimaltestdata test/xmltestdata \
test/tracedmodules test/encoded_modules \
- concurrent encodings \
+ concurrent concurrent/futures encodings \
email email/mime email/test email/test/data \
html json json/tests http dbm xmlrpc \
sqlite3 sqlite3/test \