Launchpad recipe seems to be broken

As far as I can tell this is an issue with launchpad:

https://launchpadlibrarian.net/326457370/buildlog.txt.gz

This only happens to me in Artful. The exact same recipe succeeds on other releases. Here is the recipe:

https://code.launchpad.net/~ubuntu-elisp/+recipe/emacs-25

RUN ['git-build-recipe', '--safe', '--no-build', '--manifest', '/home/buildd/build-RECIPEBRANCHBUILD-1403534/chroot-autobuild/home/buildd/work/tree/manifest', '--distribution', 'artful', '--allow-fallback-to-native', '--append-version', '~ubuntu17.10.1', '/home/buildd/build-RECIPEBRANCHBUILD-1403534/chroot-autobuild/home/buildd/work/recipe', '/home/buildd/build-RECIPEBRANCHBUILD-1403534/chroot-autobuild/home/buildd/work/tree']
resource.struct_rusage(ru_utime=239.056, ru_stime=6.624, ru_maxrss=180740, ru_ixrss=0, ru_idrss=0, ru_isrss=0, ru_minflt=169543, ru_majflt=40, ru_nswap=0, ru_inblock=11448, ru_oublock=825432, ru_msgsnd=0, ru_msgrcv=0, ru_nsignals=0, ru_nvcsw=125164, ru_nivcsw=13901)
Get:1 file:/home/buildd/work/apt ./ InRelease
Ign:1 file:/home/buildd/work/apt ./ InRelease
Get:2 file:/home/buildd/work/apt ./ Release [1329 B]
Get:2 file:/home/buildd/work/apt ./ Release [1329 B]
Get:3 file:/home/buildd/work/apt ./ Release.gpg
Ign:3 file:/home/buildd/work/apt ./ Release.gpg
Reading package lists...
E: The repository 'file:/home/buildd/work/apt ./ Release' is not signed.
Reading package lists...
E: You must put some 'source' URIs in your sources.list

I don't see anything there that I could control from my recipe. It appears to be git-build-recipe itself that is broken.