Nightly images are broken

When pulling the latest nightly and trying to run BuildStream, we receive a very unhelpful failure:

$ sudo docker pull buildstream/buildstream:nightly
nightly: Pulling from buildstream/buildstream
fd2e8b5b2254: Pull complete
02265a8a6af4: Pull complete
Digest: sha256:37aa0f032ef89232e6ec6e0a71af7db10c13f7d9c350ac8a2291d3d520484c59
Status: Downloaded newer image for buildstream/buildstream:nightly
 
 $ sudo docker run -it buildstream/buildstream:nightly
bash: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8)
/usr/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8)
/usr/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8)
/usr/bin/sh: warning: setlocale: LC_ALL: cannot change locale (en_US.UTF-8)
[root@d0c722fbfb49 /]# bst --version
Illegal instruction (core dumped)
[root@d0c722fbfb49 /]#