Ignore implied formats for catch all route requests (#1340)

A request to `/test` would show the custom 404 page, but a request to
`/test.test` would return a 404 with an empty body.

This change ignores the format on incoming catch all route requests, so that the
html 404 page is returned on these requests.

spec/requests/catch_all_route_request_spec.rb

@@ -0,0 +1,21 @@
+require "rails_helper"
+
+describe "The catch all route" do
+  describe "with a simple value" do
+    it "returns a 404 page as html" do
+      get "/test"
+
+      expect(response.status).to eq 404
+      expect(response.content_type).to eq "text/html"
+    end
+  end
+
+  describe "with an implied format" do
+    it "returns a 404 page as html" do
+      get "/test.test"
+
+      expect(response.status).to eq 404
+      expect(response.content_type).to eq "text/html"
+    end
+  end
+end