python-formencode ftbfs in 18.04 LTS

according to
http://people.canonical.com/~doko/ftbfs-report/test-rebuild-20181222-bionic.html

python-formencode ftbfs.

**********************************************************************
2 items had failures:
   6 of 6 in formencode.national.CountryValidator
   4 of 6 in formencode.national.LanguageValidator
***Test Failed*** 10 failures.

--------------------- >> end captured stdout << ----------------------

----------------------------------------------------------------------
Ran 257 tests in 1.246s

FAILED (failures=1)
E: pybuild pybuild:336: test: plugin distutils failed with: exit code=1: cd /<<PKGBUILDDIR>>/.pybuild/cpython2_2.7_formencode/build; python2.7 -m nose
dh_auto_test: pybuild --test -i python{version} -p 2.7 returned exit code 13
debian/rules:6: recipe for target 'build' failed
make: *** [build] Error 25