This Gnome software uses both DISABLE_SINGLE_INCLUDES and DISABLE_DEPRECATED which breaks with stable libunique. I have extended the sed magic in the ebuild that caught DISABLE_DEPRECATED to also catch DISABLE_SINGLE_INCLUDES. The tree commit was approved by Leio; he reports that this patch or at least a description of the problem should be relayed upstream.
Sent: https://bugzilla.gnome.org/show_bug.cgi?id=621543