message: go: Fix CentOS builds.
  Leave the system environment as it is when running Go commands.
diff: @@ -249,12 +249,11 @@ class Toolkit:
  """
  if self.__env is not False:
  return self.__env
  - self.__env = {
  - 'GO%s' % k.upper(): getattr(self, k)
  - for k in Toolkit.properties
  - if getattr(self, k) is not None
  - }
  - self.__env['PATH'] = os.environ['PATH']
  + self.__env = dict(os.environ)
  + for k in Toolkit.properties:
  + v = getattr(self, k)
  + if v is not None:
  + self.__env['GO%s' % k.upper()] = v
  return self.__env
  def run(self, cmd):
  