def current(self, calc=None, scan=1):
        self.binfo = self.gen_binfo(calc)
        if self.always_build:
            return None
        if not self.exists():
            # The file doesn't exist locally...
            r = self.rfile()
            if r != self:
                # ...but there is one in a Repository...
                old = r.get_stored_info()
                if old == self.binfo:
                    # ...and it's even up-to-date...
                    if self._local:
                        # ...and they'd like a local copy.
                        LocalCopy(self, r, None)
                        self.store_info(self.binfo)
                    return 1
            self._rfile = self
            return None
        else:
            old = self.get_stored_info()
            is_current = (old == self.binfo)
            if 1 and is_current and self.is_derived():
                import SCons.Defaults
                env = self.env or SCons.Defaults.DefaultEnvironment()
                if not env.use_build_signature():
                    return (getattr(old, 'csig', None) == self.calc_csig(calc))
            return is_current