Penal Code section 2900.5 governs the circumstances in which custody credits will be awarded. Subdivision (a) of that section provides that "in all felony and misdemeanor convictions, either by plea or by verdict, when the defendant has been in custody, including . . . any time spent in a jail, . . . all days of custody of the defendant . . . shall be credited upon his or her term of imprisonment." Subdivision (b) of section 2900.5 further states: "For the purposes of this section, credit shall be given only where the custody to be credited is attributable to proceedings related to the same conduct for which the defendant has been convicted. Credit shall be given only once for a single period of custody attributable to multiple offenses for which a consecutive sentence is imposed." In People v. Bruner (1995) 9 Cal.4th 1178, the court discussed the application of section 2900.5, subdivision (b). There, the defendant sought presentence credit on his prison term for cocaine possession where he had served presentence custodial time for a parole revocation based on the same cocaine possession as well as based on absconding from parole supervision, a dirty drug test, and theft of a credit card. The court held, consistent with two prior cases--In re Rojas (1979) 23 Cal.3d 152 and In re Joyner (1989) 48 Cal.3d 487--that "where a period of presentence custody stems from multiple, unrelated incidents of misconduct, such custody may not be credited against a subsequent formal term of incarceration if the prisoner has not shown that the conduct which underlies the term to be credited was also a 'but for' cause of the earlier restraint. Accordingly, when one seeks credit upon a criminal sentence for presentence time already served and credited on a parole or probation revocation term, he cannot prevail simply by demonstrating that the misconduct which led to his conviction and sentence was 'a' basis for the revocation matter as well." (Bruner, supra, 9 Cal.4th at pp. 1193-1194.) Under this " 'strict causation' " standard, no credit is allowed "unless the conduct leading to the sentence was the true and only unavoidable basis for the earlier custody." (Id. at p. 1192.)