ok, found

I have to disable ipv6 and install libasan

./python -E -S -m sysconfig --generate-posix-vars ;\
if test $? -ne 0 ; then \
	echo "generate-posix-vars failed" ; \
	rm -f ./pybuilddir.txt ; \
	exit 1 ; \
fi

=================================================================
==5408==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 34 byte(s) in 1 object(s) allocated from:
    #0 0x7fb085e03c08 in __interceptor_malloc (/lib64/libasan.so.5+0xefc08)
    #1 0x4d99a2 in _PyMem_RawMalloc Objects/obmalloc.c:99
    #2 0x4d9b4a in _PyMem_DebugRawAlloc Objects/obmalloc.c:2020
    #3 0x4d9ba5 in _PyMem_DebugRawMalloc Objects/obmalloc.c:2049
    #4 0x4dc354 in PyMem_RawMalloc Objects/obmalloc.c:527
    #5 0x4dc510 in _PyMem_RawStrdup Objects/obmalloc.c:613
    #6 0x652f5f in get_ctype_locale Python/preconfig.c:483
    #7 0x6560a6 in _PyPreConfig_Read Python/preconfig.c:506
    #8 0x616cde in _PyCoreConfig_ReadPreConfig Python/coreconfig.c:1342
    #9 0x620564 in _PyCoreConfig_Read Python/coreconfig.c:1378
    #10 0x65ef06 in pyinit_coreconfig Python/pylifecycle.c:740
    #11 0x65fa05 in _Py_InitializeCore Python/pylifecycle.c:786
    #12 0x42abba in pymain_init Modules/main.c:370
    #13 0x42addc in pymain_main Modules/main.c:889
    #14 0x42b2bb in _Py_UnixMain Modules/main.c:940
    #15 0x4258ee in main Programs/python.c:16
    #16 0x7fb085983412 in __libc_start_main ../csu/libc-start.c:308

Direct leak of 34 byte(s) in 1 object(s) allocated from:
    #0 0x7fb085e03c08 in __interceptor_malloc (/lib64/libasan.so.5+0xefc08)
    #1 0x4d99a2 in _PyMem_RawMalloc Objects/obmalloc.c:99
    #2 0x4d9b4a in _PyMem_DebugRawAlloc Objects/obmalloc.c:2020
    #3 0x4d9ba5 in _PyMem_DebugRawMalloc Objects/obmalloc.c:2049
    #4 0x4dc354 in PyMem_RawMalloc Objects/obmalloc.c:527
    #5 0x4dc510 in _PyMem_RawStrdup Objects/obmalloc.c:613
    #6 0x652f5f in get_ctype_locale Python/preconfig.c:483
    #7 0x6560a6 in _PyPreConfig_Read Python/preconfig.c:506
    #8 0x6585f8 in pyinit_preconfig Python/pylifecycle.c:723
    #9 0x65f8b0 in _Py_InitializeCore Python/pylifecycle.c:781
    #10 0x42abba in pymain_init Modules/main.c:370
    #11 0x42addc in pymain_main Modules/main.c:889
    #12 0x42b2bb in _Py_UnixMain Modules/main.c:940
    #13 0x4258ee in main Programs/python.c:16
    #14 0x7fb085983412 in __libc_start_main ../csu/libc-start.c:308

SUMMARY: AddressSanitizer: 68 byte(s) leaked in 2 allocation(s).
generate-posix-vars failed
make: *** [Makefile:586: pybuilddir.txt] Error 1