I'm just wondering if this is some kind of error in blender, i did a regular unwrap, and if you look at the picture, each face has different width, although in previous blender they should be the same, can any one explain this?
I opened it with the last two versions of Blender and got the same unwrap as your picture here.I’m not sure what is causing it, but I’ll see if I can figure something out.
The object is scaled in y direction in ObjectMode, so it is stretched for the Unwrapper.
Just Apply Scale and Rotation with Ctrl+A 1.
Then the Unwrap will behave as usual.