Reproduction steps:
1. Open the attached project;
2. Select object Canvas/Scroll View/Viewport/Content/GameObject/Text;
3. Change Pivot.X to 0;

Actual result: Rect Transform height doesn't adapt to the text height.
Expected result: Rect Transform height should adapt to the text height even the Pivot.X set to 0.

Reproduced with: 5.5.0f1, 5.5.0f2, 5.6.0a6
Not reproducible: 5.3.6p4, 5.4.1f1, 5.4.3f1