test-instrumentation.nix: Prevent calling a pager

Changed files
+5
nixos
modules
+5
nixos/modules/testing/test-instrumentation.nix
···
systemd.services."serial-getty@ttyS0".enable = false;
systemd.services."serial-getty@hvc0".enable = false;
+
# Don't use a pager when executing backdoor actions. Because we
+
# use a tty, commands like systemctl or nix-store get confused
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# into thinking they're running interactively.
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environment.variables.PAGER = "";
+
boot.initrd.postDeviceCommands =
''
# Using acpi_pm as a clock source causes the guest clock to