Build fails due to ruby version mismatch

Tallyho! Thanks @pfaffman

root@discuss:~# docker ps
CONTAINER ID   IMAGE                  COMMAND        CREATED       STATUS       PORTS                                                                          NAMES
f6dbb52ff74c   local_discourse/data   "/sbin/boot"   10 days ago   Up 3 hours                                                                                  data
674e5e3fe5d8   local_discourse/app    "/sbin/boot"   10 days ago   Up 3 hours   0.0.0.0:80->80/tcp, [::]:80->80/tcp, 0.0.0.0:443->443/tcp, [::]:443->443/tcp   app

Running
docker stop app; docker rm app
then
./launcher bootstrap web_only && ./launcher destroy web_only && ./launcher start web_only
works fine now

I am very curious about the “hold” on app and why previous rebuilds worked fine. Very odd.