Fails to build with --enable-unitylens-plugin

diodon no longer builds on Ubuntu "Saucy" if --enable-unitylens-plugin is set.

[34/69] libdiodon_typelib: _build_/libdiodon/Diodon-1.0.gir -> _build_/libdiodon/Diodon-1.0.typelib
/usr/share/gir-1.0/Gee-1.0.gir:8:51: warning: element annotation from state 6 is unknown, ignoring
/usr/share/gir-1.0/Gee-1.0.gir:9:53: warning: element annotation from state 6 is unknown, ignoring
[35/69] valac: diodon/main.vala -> _build_/diodon/main.c
/«PKGBUILDDIR»/plugins/unitylens/unity-lens-plugin.vala:41.17-41.26: error: The type name `Unity.Lens' could not be found
/«PKGBUILDDIR»/plugins/unitylens/unity-lens-plugin.vala:42.17-42.27: error: The type name `Unity.Scope' could not be found
/«PKGBUILDDIR»/plugins/unitylens/unity-lens-plugin.vala:181.41-181.51: error: The type name `Unity.Scope' could not be found
/«PKGBUILDDIR»/plugins/unitylens/unity-lens-plugin.vala:182.13-182.28: error: The type name `Unity.LensSearch' could not be found
/«PKGBUILDDIR»/plugins/unitylens/unity-lens-plugin.vala:188.42-188.57: error: The type name `Unity.LensSearch' could not be found
/«PKGBUILDDIR»/plugins/unitylens/unity-lens-plugin.vala:209.48-209.63: error: The type name `Unity.LensSearch' could not be found
/«PKGBUILDDIR»/plugins/unitylens/unity-lens-plugin.vala:221.55-221.70: error: The type name `Unity.LensSearch' could not be found
Waf: Leaving directory `/«PKGBUILDDIR»/_build_'
Build failed
 -> task in 'unitylens' failed (exit status 1):
 {task 37201808: valac unity-lens-plugin.vala,unity-lens-schemas.vala -> unitylens.h,unitylens.vapi,unitylens.deps,unity-lens-plugin.c,unity-lens-schemas.c}
''

ProblemType: Bug
DistroRelease: Ubuntu 13.10
Package: diodon (not installed)
ProcVersionSignature: Ubuntu 3.9.0-4.9-generic 3.9.4
Uname: Linux 3.9.0-4-generic x86_64
ApportVersion: 2.10.2-0ubuntu1
Architecture: amd64
Date: Sun Jun 9 10:01:31 2013
MarkForUpload: True
SourcePackage: diodon
UpgradeStatus: Upgraded to saucy on 2013-05-07 (32 days ago)