Staff spacing behaviour changed in 2.19

[Paul Hodges]

In the example on the documentation page 
   
http://lilypond.org/doc/v2.19/Documentation/learning/building-a-score-from-scratch
 
the command
   \override VerticalAxisGroup.staff-staff-spacing.stretchability = 5
is used to modify the spacing of the pedal staff in an organ score.


The result shown on the documentation page (which I also get at home with 
2.19.80) does not match the result on the corresponding page for 2.18, and is 
clearly wrong.


I cannot find any documentation suggesting that the usage should have changed.


Regards,
Paul