docs: 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)