Firefighters, helped by cold nighttime temperatures, expect by late today to fully contain the Butte Fire, which has burned for more than a week in the Umpqua and Deschutes national forests. The 142-acre fire was 90 percent contained this morning. The fire still had the potential to escape containment lines, but it was unlikely, fire agency spokesman Ken Malgren said. Firefighters were reinforcing fire lines and extinguishing hot spots within 150 feet of the lines. Personnel assigned to the fire had dropped to 246 from a high of 425 earlier this week. The cause of the fire is still under …