anchor.diff:      test("that's not normalized removes and returns the normalized path", () {
         set.add("root/path/to/file");
         expect(set.remove("root/../root/path/to/../to/./file"),
  -          unorderedEquals(["root/path/to/file"]));
  +          unorderedEquals([p.normalize("root/path/to/file")]));
       });
   
       test("that's absolute removes and returns the normalized path", () {
         set.add("root/path/to/file");
         expect(set.remove(p.absolute("root/path/to/file")),
  -          unorderedEquals(["root/path/to/file"]));
  +          unorderedEquals([p.normalize("root/path/to/file")]));
       });
   
       test("that's not beneath the root throws an error", () {
  
positive.code:         "root/path/to/one",
          "root/path/to/two",
          "root/path/to/sub/three"
        ]));
  
        expect(set, containsPath("root/outside"));
        expect(set, isNot(containsPath("root/path/to/one")));
  
negative.code:         "root/path",
          "root/path/to/one",
          "root/path/to/two",
        ].map(p.normalize)));
      });
  
      test("doesn't return paths removed from the set", () {
  