Try to start any builds that can be started right now.  This function
        returns immediately, and promises to trigger those builders
        eventually.

        @param new_builders: names of new builders that should be given the
        opportunity to check for new requests.

def maybeStartBuildsOn(self, new_builders):
        """
        Try to start any builds that can be started right now.  This function
        returns immediately, and promises to trigger those builders
        eventually.

        @param new_builders: names of new builders that should be given the
        opportunity to check for new requests.
        """
        if not self.running:
            return

        d = self._maybeStartBuildsOn(new_builders)
        self._pendingMSBOCalls.append(d)

        try:
            yield d
        except Exception as e:  # pragma: no cover
            log.err(e, "while starting builds on {0}".format(new_builders))
        finally:
            self._pendingMSBOCalls.remove(d)