input/regression/page-layout-twopass.ly

[Graham Percival]

I'm trying to learn about two-pass spacing so I can add it to the 
manual.  How am I supposed to use the example file?  When I run it for 
the first time ("lilypond page-layout-twopass.ly"), it produces a
page-layout-twopass-page-layout.ly
file, but when I run lilypond again, it just produces another such 
file, and the output looks the same.

- Graham