The 2012-12-31 of this patch (currently the latest) has the surprising effect of causing distutils CFLAGS to be dropped.  See for reference: https://bugs.gentoo.org/show_bug.cgi?id=548776

The issue I am experiencing is resolved by changing the section of the patch that reads:

+-        (cc, cxx, opt, cflags, ccshared, ldshared, shlib_suffix, ar, ar_flags) = \
+-            get_config_vars('CC', 'CXX', 'OPT', 'CFLAGS',
+-                            'CCSHARED', 'LDSHARED', 'SHLIB_SUFFIX', 'AR', 'ARFLAGS')
++        (cc, cxx, ccshared, ldshared, ldcxxshared, shlib_suffix, ar, ar_flags) = \
++            get_config_vars('CC', 'CXX', 'CCSHARED', 'LDSHARED', 'LDCXXSHARED',
++                            'SHLIB_SUFFIX', 'AR', 'ARFLAGS')
++
++        cflags = ''
++        cxxflags = ''

to:

+-        (cc, cxx, opt, cflags, ccshared, ldshared, shlib_suffix, ar, ar_flags) = \
+-            get_config_vars('CC', 'CXX', 'OPT', 'CFLAGS',
+-                            'CCSHARED', 'LDSHARED', 'SHLIB_SUFFIX', 'AR', 'ARFLAGS')
++        (cc, cxx, cflags, ccshared, ldshared, ldcxxshared, shlib_suffix, ar, ar_flags) = \
++            get_config_vars('CC', 'CXX', 'CFLAGS', 'CCSHARED', 'LDSHARED', 'LDCXXSHARED',
++                            'SHLIB_SUFFIX', 'AR', 'ARFLAGS')
++
++        cxxflags = cflags

This change causes the CFLAGS outputted by "python-config --cflags" to be used by distutils, as they are without the patch applied.  To me, losing those CFLAGS, especially when building plain C python extensions, seems like a significant regression.