The problem was that a continous section break at the end of the
document caused the section margins to be ignored. Just ignoring the
continous section break (only in case it's at the end of the document)
makes the problem go away.

The original fix was commit cd1c434c,
but it got reverted in commit 2dee7d62,
as it caused fdo#44292. This second attempt fixes the original bug
again, without introducing the "4 columns" bug.

Change-Id: I75d612430a5cd631dec0d224127cba580070900d