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/mailcatcher.nix

@@ -0,0 +1,35 @@
+import ./make-test-python.nix ({ lib, ... }:
+
+{
+  name = "mailcatcher";
+  meta.maintainers = [ lib.maintainers.aanderse ];
+
+  nodes.machine =
+    { pkgs, ... }:
+    {
+      services.mailcatcher.enable = true;
+
+      programs.msmtp = {
+        enable = true;
+        accounts.default = {
+          host = "localhost";
+          port = 1025;
+        };
+      };
+
+      environment.systemPackages = [ pkgs.mailutils ];
+    };
+
+  testScript = ''
+    start_all()
+
+    machine.wait_for_unit("mailcatcher.service")
+    machine.wait_for_open_port("1025")
+    machine.succeed(
+        'echo "this is the body of the email" | mail -s "subject" root@example.org'
+    )
+    assert "this is the body of the email" in machine.succeed(
+        "curl -f http://localhost:1080/messages/1.source"
+    )
+  '';
+})