setup.py

--- a/setup.py	Fri Aug 12 11:30:17 2016 +0900
+++ b/setup.py	Fri Aug 12 11:35:17 2016 +0900
@@ -641,7 +641,7 @@
                                     'mercurial/pathencode.c'],
               include_dirs=common_include_dirs,
               depends=common_depends),
-    Extension('mercurial.osutil', ['mercurial/osutil.c'],
+    Extension('mercurial.cext.osutil', ['mercurial/cext/osutil.c'],
               include_dirs=common_include_dirs,
               extra_compile_args=osutil_cflags,
               extra_link_args=osutil_ldflags,