merge the end_fd comment fix and explicit wait() for the child.

Lib/test/test_subprocess.py

@@ -1966,7 +1966,7 @@ class POSIXProcessTestCase(BaseTestCase):
                      import subprocess, sys
                      subprocess.Popen([sys.executable, {fd_status!r}] +
                                       [str(x) for x in range({max_fd})],
-                                      close_fds=True)
+                                      close_fds=True).wait()
                      """.format(fd_status=fd_status, max_fd=max_fd_open+1))],
                 stdout=subprocess.PIPE, close_fds=False)
         finally:

Modules/_posixsubprocess.c

@@ -234,8 +234,8 @@ struct linux_dirent64 {
    char           d_name[256];  /* Filename (null-terminated) */
 };
 
-/* Close all open file descriptors in the range start_fd inclusive to end_fd
- * exclusive. Do not close any in the sorted py_fds_to_keep list.
+/* Close all open file descriptors in the range from start_fd and higher
+ * Do not close any in the sorted py_fds_to_keep list.
  *
  * This version is async signal safe as it does not make any unsafe C library
  * calls, malloc calls or handle any locks.  It is _unfortunate_ to be forced