diff -r 7c98768368cb Python/fileutils.c
--- a/Python/fileutils.c	Sat Nov 19 01:06:37 2016 +0000
+++ b/Python/fileutils.c	Sat Nov 19 15:22:57 2016 +0100
@@ -886,7 +886,7 @@
         return 0;
     }
 
-    res = fcntl(fd, F_SETFD, flags);
+    res = fcntl(fd, F_SETFD, new_flags);
     if (res < 0) {
         if (raise)
             PyErr_SetFromErrno(PyExc_OSError);