Mayor Bill de Blasio is now condemning the pot-friendly approach of Ben Sherman, the principal at Forest Hills HS, but his own policies point in the same direction.

In Sunday’s Post, Susan Edelman exposed Sherman’s shocking indifference to students toking in school, on the grounds that marijuana is “going to be legal soon.”

Huh? It won’t be legal for kids — and even if it were, it still has no place in school.

Teachers complain of how pungent pot odors regularly permeate the Forest Hills air. And students on Monday confirmed to Post reporters how nonchalant Sherman is about it all.

De Blasio calls it “unallowable and unacceptable” that the one-time National Blue Ribbon school has literally gone to pot. But his own discipline “reforms” point in Sherman’s direction: The mayor’s drive to end student suspensions has mandated non-punitive responses to student misbehavior.

Toking is prohibited at all schools, but cops and safety agents may only give kids 16 or older a “warning card,” not a summons. Sherman is only taking this another step.

Kudos to the Forest Hills HS branch of the United Federation of Teachers for pushing for Sherman’s ouster. Maybe it’ll inspire the whole UFT to condemn de Blasio’s discipline dementia.