normalize_path used to be nil tolerant

fixes a regression introduced at 8607c25b

actionpack/lib/action_dispatch/journey/router/utils.rb

@@ -13,6 +13,7 @@ class Utils # :nodoc:
         #   normalize_path("")      # => "/"
         #   normalize_path("/%ab")  # => "/%AB"
         def self.normalize_path(path)
+          path ||= ''
           encoding = path.encoding
           path = "/#{path}".dup
           path.squeeze!("/".freeze)

actionpack/test/journey/router/utils_test.rb

@@ -38,6 +38,10 @@ def test_normalize_path_maintains_string_encoding
           path = "/foo%AAbar%AAbaz".b
           assert_equal Encoding::ASCII_8BIT, Utils.normalize_path(path).encoding
         end
+
+        def test_normalize_path_with_nil
+          assert_equal '/', Utils.normalize_path(nil)
+        end
       end
     end
   end