Ignore empty parameters in type_params

lib/net/http/header.rb

@@ -800,6 +800,7 @@ def type_params
     list = self['Content-Type'].to_s.split(';')
     list.shift
     list.each do |param|
+      next if param.strip.empty?
       k, v = *param.split('=', 2)
       result[k.strip] = v.strip
     end

test/net/http/test_http.rb

@@ -1447,6 +1447,12 @@ def test_response_body_encoding_true_with_content_type
     assert_equal(Encoding::UTF_8, res.body.encoding)
   end
 
+  def test_response_body_encoding_true_with_trailing_semicolon_in_content_type
+    res = fe_request(true, 'text/html; charset=utf-8; ')
+    assert_equal("hello\u1234", res.body)
+    assert_equal(Encoding::UTF_8, res.body.encoding)
+  end
+
   def test_response_body_encoding_string_without_content_type
     res = fe_request('utf-8')
     assert_equal("hello\u1234", res.body)

test/net/http/test_httpheader.rb

@@ -512,6 +512,10 @@ def test_type_params
     assert_equal({'charset' => 'iso-2022-jp'}, @c.type_params)
     @c.content_type = 'text'
     assert_equal({}, @c.type_params)
+    @c['content-type'] = 'text/html; charset=utf-8; '
+    assert_equal({'charset' => 'utf-8'}, @c.type_params)
+    @c['content-type'] = 'text/html;'
+    assert_equal({}, @c.type_params)
   end
 
   def test_set_content_type