Failed to run `gen.site` with `--host` on existing site in a scope without opts

[leandrocp]

Given this existing scope:

  scope "/blog" do
    pipe_through [:browser, :beacon]
    beacon_site "/", site: :blog
  end

Running mix beacon.gen.site --site blog --host blog.mysite.com failed with:

** (FunctionClauseError) no function clause matching in Mix.Tasks.Beacon.Gen.Site.add_host_to_scope/2

    The following arguments were given to Mix.Tasks.Beacon.Gen.Site.add_host_to_scope/2:

        # 1
        {:scope, [trailing_comments: [], leading_comments: [], end_of_expression: [newlines: 2, line: 37, column: 6], do: [line: 34, column: 17], end: [line: 37, column: 3], line: 34, column: 3], [{:__block__, [trailing_comments: [], leading_comments: [], delimiter: "\"", line: 34, column: 9], ["/blog"]}, [{{:__block__, [trailing_comments: [], leading_comments: [], line: 34, column: 17], [:do]}, {:__block__, [trailing_comments: [], leading_comments: []], [{:pipe_through, [trailing_comments: [], leading_comments: [], end_of_expression: [newlines: 1, line: 35, column: 37], line: 35, column: 5], [{:__block__, [trailing_comments: [], leading_comments: [], closing: [line: 35, column: 36], line: 35, column: 18], [[{:__block__, [trailing_comments: [], leading_comments: [], line: 35, column: 19], [:browser]}, {:__block__, [trailing_comments: [], leading_comments: [], line: 35, column: 29], [:beacon]}]]}]}, {:beacon_site, [trailing_comments: [], leading_comments: [], end_of_expression: [newlines: 1, line: 36, column: 33], line: 36, column: 5], [{:__block__, [trailing_comments: [], leading_comments: [], delimiter: "\"", line: 36, column: 17], ["/"]}, [{{:__block__, [trailing_comments: [], leading_comments: [], format: :keyword, line: 36, column: 22], [:site]}, {:__block__, [trailing_comments: [], leading_comments: [], line: 36, column: 28], [:blog]}}]]}]}}]]}

        # 2
        "blog.mysite.com"

    Attempted function clauses (showing 1 out of 1):

        defp add_host_to_scope({:scope, scope, [scope_path, scope_opts, rest]}, host)

    (beacon 0.4.0) lib/mix/tasks/beacon.gen.site.ex:279: Mix.Tasks.Beacon.Gen.Site.add_host_to_scope/2
    (sourceror 1.7.1) lib/sourceror/zipper.ex:295: Sourceror.Zipper.update/2
    (beacon 0.4.0) lib/mix/tasks/beacon.gen.site.ex:271: anonymous fn/4 in Mix.Tasks.Beacon.Gen.Site.mount_site_in_router/5