What is the test for a motion to vacate a judgment in the Superior Court of Appeal while an appeal is pending?

^[4] People v. Alanis (2008) 158 Cal.App.4th 1467, 1472-1473 explains, [b]ecause an appeal divests the trial court of subject matter jurisdiction, the court lacks jurisdiction to vacate the judgment or make any order affecting it. [Citations.] Thus, action by the trial court while an appeal is pending is null and void. [Citations.] Indeed, [s]o complete is this loss of jurisdiction effected by the appeal that even the consent of the parties has been held ineffective to reinvest the trial court with jurisdiction over the subject matter of the appeal and that an order based upon such consent would be a nullity.' [Citation.]