Seting staff-staff-spacing in a \with block causes type check error

[Reinhold Kainhofer]

The attached minimal testcase (stripped down from an example in our docs) 
prints a type-check warning for a nested property:

address@hidden:~/lilypond/lilypond$ LANGUAGE=C lilypond staff-staff-
spacing-list.ly 
GNU LilyPond 2.15.12
Processing `staff-staff-spacing-list.ly'
Parsing...
Interpreting music... 
warning: type check for `staff-staff-spacing' failed; value `((stretchability 
. 5) . #<primitive-procedure ly:axis-group-interface::calc-staff-staff-
spacing>)' must be of type `list'
Preprocessing graphical objects...
Finding the ideal number of pages...
Fitting music on 1 page...
Drawing systems...
Layout output to `staff-staff-spacing-list.ps'...
Converting to `./staff-staff-spacing-list.pdf'...
Success: compilation successfully completed


This should actually not happen, so I guess the type check is not general 
enough to handle nested context props.

Cheers,
Reinhold

-- 
------------------------------------------------------------------
Reinhold Kainhofer, address@hidden, http://reinhold.kainhofer.com/
 * Financial & Actuarial Math., Vienna Univ. of Technology, Austria
 * http://www.fam.tuwien.ac.at/, DVR: 0005886
 * LilyPond, Music typesetting, http://www.lilypond.org

staff-staff-spacing-list.ly
Description: Text Data