In what circumstances will a defendant plead guilty to a charge of burglary pursuant to a plea agreement?

In Jackson, the defendant pleaded guilty to second degree burglary pursuant to a plea agreement in which the People promised to move for the dismissal of a second count of burglary and "not oppose reduction to a misdemeanor at time of sentencing if no prior record. Six months maximum." (People v. Jackson, supra, 103 Cal.App.3d 635, 637.) The trial court approved the plea agreement, taking care to explain to the defendant that the proposed sentence was conditioned upon his having no prior record. The defendant said he understood. After the probation report subsequently revealed that the defendant had an extensive prior criminal record, the court sentenced him to a term of three years in prison.