Guix Deploy not respecting `build-locally?` field in `machine-ssh-configuration`

[Lobo Torres]

Hi,

I'm using the deploy utilities to manage a Raspberry Pi 4 running Guix System.

The configuration for said system[1] involves compiling a custom kernel, which 
I first tried to do normally (by running `guix deploy rpi4-deploy.scm` [2]), 
which compiled the kernel using the native compilation, which was awfully 
slow... I didn't bother to let it finish, I left it overnight and after 10 
hours it was still building.

[1] The system configuration being deployed: 
https://quiltro.org/junk/rpi4.scm.html
[2] The deployment file used: https://quiltro.org/junk/rpi4-deploy.scm.html

I asked on the #guix IRC channel and I was told that adding `(build-locally? 
#f)` to my `machine-ssh-configuration` object would work, as it would tell Guix 
to build any derivations on the target machine, so I added that, went to deploy 
again, and Guix was still doing the build locally via QEMU.

Out of the bat I'm not sure why this is happening, disabling the `qemu-binfmt` 
service of course fails to build because the host machine is not aarch64-linux.

If something needs more explanation, please feel free to ask! English is not my 
native language so I might have explained some things weirdly.

Thanks!
---
Lobo Torres
https://quiltro.org