uboot: (firmwareOdroidC2/C4) don't invoke patch tool, use patches = [] instead

https://github.com/NixOS/nixpkgs/blob/master/pkgs/stdenv/generic/setup.sh#L948
this can do it nicely.

Signed-off-by: Anton Arapov <anton@deadbeef.mx>

nixos/tests/zrepl.nix

@@ -0,0 +1,66 @@
+import ./make-test-python.nix (
+  {
+    nodes.host = {config, pkgs, ...}: {
+      config = {
+        # Prerequisites for ZFS and tests.
+        boot.supportedFilesystems = [ "zfs" ];
+        environment.systemPackages = [ pkgs.zrepl ];
+        networking.hostId = "deadbeef";
+        services.zrepl = {
+          enable = true;
+          settings = {
+            # Enable Prometheus output for status assertions.
+            global.monitoring = [{
+              type = "prometheus";
+              listen = ":9811";
+            }];
+            # Create a periodic snapshot job for an ephemeral zpool.
+            jobs = [{
+              name = "snap_test";
+              type = "snap";
+
+              filesystems."test" = true;
+              snapshotting = {
+                type = "periodic";
+                prefix = "zrepl_";
+                interval = "1s";
+              };
+
+              pruning.keep = [{
+                type = "last_n";
+                count = 8;
+              }];
+            }];
+          };
+        };
+      };
+    };
+
+    testScript = ''
+      start_all()
+
+      with subtest("Wait for zrepl and network ready"):
+          host.wait_for_unit("network-online.target")
+          host.wait_for_unit("zrepl.service")
+
+      with subtest("Create test zpool"):
+          # ZFS requires 64MiB minimum pool size.
+          host.succeed("fallocate -l 64MiB /root/zpool.img")
+          host.succeed("zpool create test /root/zpool.img")
+
+      with subtest("Check for completed zrepl snapshot"):
+          # zrepl periodic snapshot job creates a snapshot with this prefix.
+          host.wait_until_succeeds("zfs list -t snapshot | grep -q zrepl_")
+
+      with subtest("Verify HTTP monitoring server is configured"):
+          out = host.succeed("curl -f localhost:9811/metrics")
+
+          assert (
+              "zrepl_version_daemon" in out
+          ), "zrepl version metric was not found in Prometheus output"
+
+          assert (
+              "zrepl_zfs_snapshot_duration_count{filesystem=\"test\"}" in out
+          ), "zrepl snapshot counter for test was not found in Prometheus output"
+    '';
+  })