dead_code_tests: add skip inherit test

src/dead_code_tests.rs

@@ -297,6 +297,19 @@ alive
     assert_eq!(0, results.len());
 }
 
+#[test]
+fn skip_inherit() {
+    let results = run("
+let
+  # deadnix: skip
+  inherit dead1;
+  inherit dead2;
+in alive
+    ");
+    assert_eq!(1, results.len());
+    assert_eq!(results[0].binding.name.to_string(), "dead2");
+}
+
 #[test]
 fn shadowed_by_skip() {
     let nix = "