Change of line-width in docs

[Trevor Daniels]

I've just noticed that the line-width, set in
the paper block in ly fragments in the docs,
has changed recently.  The latest development
release on lilypond.org has

\paper {
 #(define dump-extents #t)
 line-width = 160\mm - 2.0 * 0.4\in
 ragged-right = ##t
 indent = 0\mm
 force-assignment = #""
 line-width = #(- line-width (* mm  3.000000))
}

but the kainhofer server has

\paper {
 #(define dump-extents #t)
 line-width = 5\in - 2.0 * 0.4\in
 ragged-right = ##t
 indent = 0\mm
 force-assignment = #""
 line-width = #(- line-width (* mm  3.000000))
}

The change from 160\mm to 5\in shortens the line
by around 33\mm, which wrecks at least one
example - the Real music example in LM 4.5.3 -
by splitting it onto two lines.  Part of the
text no longer correctly describes the appearance 
of the music.

I could fix this by specifying line-width in the 
@lilypond call, but before I do I'd like to
understand the reason for the change.  Was the
reduction in line-width intentional?  I've
searched for this change in git, but can't find 
it.

Trevor