Comment 8 for bug 341216

Probably Gnucash should switch entirely to Guile 1.8, but this requires some changes:

It is possible to build Gnucash against Guile 1.8 with following changes to the gnucash package:
1.) Change build-dep on guile-1.6-dev to guile-1.8-dev
2.) Drop build-dep on guile-1.8-slib because it's not available (see comment below)
3.) Drop dependency on guile-1.6-slib from package gnucash
    (should be guile-1.8-slib, but that is not available, see comment below)
4a) ship a symbolic link /usr/share/guile/1.8/ pointing to ../../slib
4b) run the following command from postinst script:
    guile-1.8 -c "(use-modules (ice-9 slib)) (require 'new-catalog)"
4c) remove the symbolic links created by the postinst script in prerm script:
    rm -f /usr/share/guile/1.8/slib
    rm -f /usr/share/guile/1.8/slibcat
5.) Remove GUILE=/usr/bin/guile-1.6 from build environment
    (otherwise fails to build if guile-1.6 isn't installed)

A cleaner solution for steps 2 to 4 would be to provide a proper package guile-1.8-slib (see Debian bug http://bugs.debian.org/441110) which is doing these steps.