First system on a page may not fit to the page
Steps to reproduce:
1. Open this score (from #278783: Parts of score fall off page or are shown twice after adjusting stretch).
2. Select measures from 17 to 23.
3. Scroll to the page 4 to be able to see what happens there.
4. Press '}' (increase stretch) several times — for me 3 times reproduce the bug.
Result: the first system of the page 4 shift too high and too left to fit to the page:
This result under similar conditions is also reproducible in the first alpha version of MuseScore 3.