openSUSE Factory is in progress of merging GLIBC 2.27 - python3-base is amongst
the packages failing to build

from the build log
[ 3308s] ======================================================================
[ 3308s] ERROR: test_float_with_comma (test.test_float.GeneralFloatCases)
[ 3308s] ----------------------------------------------------------------------
[ 3308s] Traceback (most recent call last):
[ 3308s]   File
"/home/abuild/rpmbuild/BUILD/Python-3.6.4/Lib/test/support/__init__.py", line
1588, in inner
[ 3308s]     return func(*args, **kwds)
[ 3308s]   File
"/home/abuild/rpmbuild/BUILD/Python-3.6.4/Lib/test/test_float.py", line 150, in
test_float_with_comma
[ 3308s]     if not locale.localeconv()['decimal_point'] == ',':
[ 3308s]   File "/home/abuild/rpmbuild/BUILD/Python-3.6.4/Lib/locale.py", line
110, in localeconv
[ 3308s]     d = _localeconv()
[ 3308s] UnicodeDecodeError: 'locale' codec can't decode byte 0xa0 in position
0: Invalid or incomplete multibyte or wide character
[ 3308s] 
[ 3308s] ----------------------------------------------------------------------

Complete build log at
https://build.opensuse.org/package/live_build_log/openSUSE:Factory:Staging:C/python3-base/standard/x86_64