After this patch, test_distutils failed if $CPPFLAGS is not empty when building CPython. For example:

$ export CPPFLAGS=-DFOO=BAR
$ ./configure
$ make
$ ./python -m test test_distutils   
Run tests sequentially
0:00:00 load avg: 0.45 [1/1] test_distutils
test test_distutils failed -- Traceback (most recent call last):
  File "/home/yen/Projects/cpython/Lib/distutils/tests/test_sysconfig.py", line 99, in test_customize_compiler
    self.assertEqual(comp.exes['compiler'], 'my_cc --sysconfig-cflags --mycflags')
AssertionError: 'my_cc --sysconfig-cflags --mycflags -DFOO=BAR' != 'my_cc --sysconfig-cflags --mycflags'
- my_cc --sysconfig-cflags --mycflags -DFOO=BAR
?                                    ----------
+ my_cc --sysconfig-cflags --mycflags


test_distutils failed

== Tests result: FAILURE ==

1 test failed:
    test_distutils

Total duration: 2 sec 192 ms
Tests result: FAILURE

Tested with commit d2fdd1fedf6b9dc785cf5025b548a989faed089a.

This is an issue as Arch Linux uses CPPFLAGS="-D_FORTIFY_SOURCE=2" for creating packages [1].

[1] https://git.archlinux.org/svntogit/packages.git/tree/trunk/makepkg.conf?h=packages/pacman#n39