message: Test that homepage/documentation values are properly propagated
diff: @@ -1179,6 +1179,8 @@ fn package_metadata() {
  keywords = ["database"]
  readme = "README.md"
  repository = "https://github.com/rust-lang/cargo"
  + homepage = "https://rust-lang.org"
  + documentation = "https://doc.rust-lang.org/stable/std/"
  [package.metadata.bar]
  baz = "quux"
  @@ -1199,8 +1201,8 @@ fn package_metadata() {
  "name": "foo",
  "readme": "README.md",
  "repository": "https://github.com/rust-lang/cargo",
  - "homepage": null,
  - "documentation": null,
  + "homepage": "https://rust-lang.org",
  + "documentation": "https://doc.rust-lang.org/stable/std/",
  "version": "0.1.0",
  "id": "foo[..]",
  "keywords": ["database"],
  