Do not add `:include_blank` option if prompt is present

actionpack/lib/action_view/helpers/tags/base.rb

@@ -121,7 +121,7 @@ def sanitized_value(value)
         def select_content_tag(option_tags, options, html_options)
           html_options = html_options.stringify_keys
           add_default_name_and_id(html_options)
-          options[:include_blank] ||= true if option_required?(html_options)
+          options[:include_blank] ||= true unless options[:prompt] || select_not_required?(html_options)
           select = content_tag("select", add_options(option_tags, options, value(object)), html_options)
 
           if html_options["multiple"] && options.fetch(:include_hidden, true)
@@ -131,8 +131,8 @@ def select_content_tag(option_tags, options, html_options)
           end
         end
 
-        def option_required?(html_options)
-          html_options["required"] && !html_options["multiple"] && !(html_options["size"].to_i > 1)
+        def select_not_required?(html_options)
+          !html_options["required"] || html_options["multiple"] || html_options["size"].to_i > 1
         end
 
         def add_options(option_tags, options, value = nil)

actionpack/test/template/form_options_helper_test.rb

@@ -648,6 +648,13 @@ def test_required_select_with_include_blank_prompt
     )
   end
 
+  def test_required_select_with_prompt
+    assert_dom_equal(
+      %(<select id="post_category" name="post[category]" required="required"><option value="">Select one</option>\n<option value="abe">abe</option>\n<option value="mus">mus</option>\n<option value="hest">hest</option></select>),
+      select("post", "category", %w(abe mus hest), { prompt: "Select one" }, required: true)
+    )
+  end
+
   def test_required_select_display_size_equals_to_one
     assert_dom_equal(
       %(<select id="post_category" name="post[category]" required="required" size="1"><option value=""></option>\n<option value="abe">abe</option>\n<option value="mus">mus</option>\n<option value="hest">hest</option></select>),