nixos tests: waitForText: output the detected screen content prior to the last attempt

    machine: Last chance to match /(?^:BALICE)/ on the screen, which currently contains:
    machine: performing optical character recognition
    machine: sending monitor command: screendump /tmp/nix-build-vm-test-run-sddm.drv-0/ocrin.ppm
    machine: Session Layout

    O O

    0 1 : 0 9

    Wednesday, June 21, 2017

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