Pages are not positioned correctly when using shortcuts "Page Up" and "Page Down"

Open the score test-navigator.mscz (created with MuseScore d75fb33 on Xubuntu 14.10).

Set the zoom to "Page Width".

By default, the first page is positioned correctly. The left and right edges of the page correspond exactly to the limit of the score view:

Press "Page Down" to display the page 2.

Result: the page 2 is shifted right instead of fitting exactly the score view:

Press "Page Down" to display the page 3.

Result: the page 3 is shifted right instead of fitting exactly the score view.

Press "Page Up" twice to display the page 1.

Result: the page 1 is shifted right instead of fitting exactly the score view.