class Base(object):
    def dispatch(self, request, *args, **kwargs):
        if request.user.is_superuser:
            return super(Base, self).dispatch(request, *args, **kwargs)
        try:
            p = Plumbing.objects.all()[0].is_closed
            if p:
                self.template_name = "plumbing.html"
        except IndexError:
            pass
        return super(Base, self).dispatch(request, *args, **kwargs)

p = Plumbing.objects.all()[0].is_closed

p = Plumbing.objects.all()[0]
if p:

p = Plumbing.objects.all()[0]
print p
if p:
    Условие выполняется

p = Plumbing.objects.all()[0]
if p:
    А без принта не выполняется :)

for item in useful_container:
    #...
    if something in useful_container:
        """..."""
    #...