Issue #15392: Install idlelib/idle_test.
diff --git a/Makefile.pre.in b/Makefile.pre.in
index 27dd75f..5f677c8 100644
--- a/Makefile.pre.in
+++ b/Makefile.pre.in
@@ -1048,7 +1048,8 @@
lib2to3 lib2to3/fixes lib2to3/pgen2 lib2to3/tests \
lib2to3/tests/data lib2to3/tests/data/fixers \
lib2to3/tests/data/fixers/myfixes \
- ctypes ctypes/test ctypes/macholib idlelib idlelib/Icons \
+ ctypes ctypes/test ctypes/macholib \
+ idlelib idlelib/Icons idlelib/idle_test \
distutils distutils/command distutils/tests $(XMLLIBSUBDIRS) \
importlib test/test_importlib test/test_importlib/builtin \
test/test_importlib/extension test/test_importlib/frozen \