Question: in the 1979–80 NBA season, Philadelphia 76ers acquired a guard from the Portland Trail Blazers who has recently served as a head coach of which NBA team ?
Sentence (from "1979–80 Philadelphia 76ers season"): The 1979–1980 Philadelphia 76ers season was the 76ers 31st season in the National Basketball Association (NBA) and 17th season in Philadelphia.
Relevant evidence: No