3b8cd8ad70
PR #256638 inadvertently introduced a bug in `nixos-generate-config` whereby it would never put `bcache` into the `availableKernelModules` for the initrd. This is because the `qr` operator in Perl returns a regex object, rather than matching it; the regex object evaluates to true, making the filter expression effectively `grep(!true, @bcacheDevices)`, which will always return an empty list.