SSH runs the command provided to it in the user's login shell.
That's a feature and is impossible to bypass (trust me, we tried).
The previous implementation of `echo started; nix-store --stdio`
broke with shells that treat `;` differently, e.g. nushell,
which eats the output of everything but the last command in a chain.
In the more general case, this means that a sufficiently weird shell
can do _anything_ it wants to the command we pass via SSH, so
we're forced to rely on as little functionality as possible.
The subset we're hereby settling on is just "running `bash` runs bash".
We then run bash, in non-interactive mode, which gives us a somewhat
consistent environment do to things in.
This whole thing is extremely cursed, but fixing it _correctly_
requires pretty much entirely rewriting how remote stores work,
and I'm not doing that right now.
Fixes#805.
Change-Id: Icac846e8cd821cbca91860ddaa0f657b4317dbf8
Co-authored-by: eldritch horrors <pennae@lix.systems>
