Some OS don't support the way systemd is dealing with keymaps (e.g.
Debian, see https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=790955).
If we try to set the keymap using `systemd-firstboot --keymap`, this
will fail, and the error message from `systemd-firstboot` is misleading:
it states that the keymap is not installed.
I couldn't find out how to reliably detect if systemd's keymap
management is supported, so instead, we provide a hint in the error
message if `systemd-firstboot --keymap` fails that the reason could be
that it's unsupported.
Fixes#2904
More generic keymap/systemd error message + dedent
Adds test of warning if keymap setting unsupported
Fix linter complaints about formatting
Run keymap check under chroot
We're interested in the capabilities of the target system, since we also
run `systemd-firstboot --keymap` in there.
Fixup for setup_test after chroot'ing localectl
Remove localectl call
It talks to systemd.
Fix tests for keymap
845b5270b8