Well, I never needed to do that manually to run cucumber, but I needed to do it in some other cases, sometimes …
So it looks like sometimes rails does this automatically or doesn’t require it. But if it needs it, it shows you that it needs it (including the command), so I think that’s fine.
It also doesn’t hurt to run it anyway in the setup, does it?
Maybe we could also add a command to launch the rails console inside docker?
Anyway, it solved the crash, but the tests still aren’t running, stuck on the first step, nothing happening:
Interesting, it does the same for me, but it works outside docker … maybe something is missing in the container? But also weird that it just hangs and doesn’t show any errors anywhere. 
Another need which should be described or handled: how to modified diaspora.toml? I tried script/diaspora-dev exec vi config/diaspora.toml but vi isn’t available, neither is nano.
Well, the whole diaspora folder is just mounted inside the container, so you can just edit source-code and configs with your normal editor. Nothing special needed there.
@flaburgan A little heads up for when you are pulling develop:
script/diaspora-dev docker-compose down -v (this will wipe all volumes used by diaspora) and then script/diaspora-dev setup again.