tests/test-gendoc-pt_BR.t

setup: fix a possible NameError on rust build

  File "setup.py", line 975, in rustbuild
    "command: %r, environment: %r" % (self.rustsrcdir, cmd, env))
NameError: global name 'cmd' is not defined

#require docutils gettext

  $ $TESTDIR/check-gendoc pt_BR
  checking for parse errors