A. A prisoner in a city, town or county jail, while working on the public streets, highways or other public works as a trusty outside the jail without requiring armed guards, or while holding a position of trust either within or without the jail, shall be allowed double time while so employed and each day he is so employed shall be counted as two days in computing time on his sentence except in cases in which a specific release date is set forth in the commitment.
B. In case of a breach of trust by a prisoner, the chief of police or sheriff may declare the double time forfeited.