They are already excluded while moving the cursor using a condition that
seems to accidentally not match, but this is more explicit and works
around the behavior of gr-cursor-manager that it clamps to the first/
last cursor stop even if that first/last cursor stop does not fullfill
the condition. Changing that might have other side-effects.
Concretely this fixes a bug where you can move the cursor to the
context line at the end of a diff.
Change-Id: Ibe49782d6b10ddfafe07d09dea64718622503f72
5265fc57f4