I believe it could go either way depending on the plans. Some roof systems rely on a rough fascia to support the roof system... ie: stick built 4' o.c. for metal roofing. But, if the overhang is not huge remember that the truss or ceiling joist is tied to the top of the wall and the top cord of the truss or joist is tied to the roof sheathing. There's not a whole lot of room for twisting here. In some cases a finish fascia will provide plenty of structure and therefor is not part of rough framing.
I personally like a rough fascia as part of the roof system for several reasons... this helps the roof system from moving, provides a nice backer for a thin outer soffit strips so then vents can go in the proper position, and helps resist wind in the building prior to finish fascia work. This really should be planned ahead so that the gable overhang can match the rest and wont be offset by the thickness of the rough fascia (not that anyone but the builder would notice
I have also seen this slip through the cracks in building and inspection when roof systems are changed on the fly from say stick built prints to engineered trusses.
Quite frankly this is one of the many little details that the owner builder gets in trouble with by not knowing enough to ask in the beginning. Choose your battles with your framer, there's usually room for give and take. Good luck.