Reproduction Steps:
1. Open "Bug" project
2. Open "Bitmap_Font_Scale_Issue" scene
3. Noice that "Actual Result (when scaling a bitmap font in layout group)" child "txt_title" Layout Element preferred width is 325.
4. Notice that Horizontal Layout Group allocates double the given size 650x100
5. Investigate "Test" scene

Expected Behaviour: Layout group allocates the proper size according to its child Layout Elements Preferred values.
Actual Result: Layout group allocates double the size that is set in its child Layout Element preferred fields.

Reproduced on versions: Unity 5.4.1f1, 5.4.5p3, 5.5.4f1, 5.6.1p4, 2017.1.0b10, 2017.2.0a4