Do nothing when the same block is included again.

If the same block is included multiple times, we no longer raise an exception
or overwrite the included block instance variable.

Fixes #14802.

[Mark J. Titorenko + Vlad Bokov]

2 files changed, 19 insertions, 0 deletions

diff --git a/activesupport/test/concern_test.rb b/activesupport/test/concern_test.rb
index 98d8f3ee0d..4b3cfcd1d2 100644
--- a/activesupport/test/concern_test.rb
+++ b/activesupport/test/concern_test.rb
@@ -128,4 +128,12 @@ class ConcernTest < ActiveSupport::TestCase
       end
     end
   end
+
+  def test_no_raise_on_same_included_call
+    assert_nothing_raised do
+      2.times do
+        load File.expand_path("../fixtures/concern/some_concern.rb", __FILE__)
+      end
+    end
+  end
 end
diff --git a/activesupport/test/fixtures/concern/some_concern.rb b/activesupport/test/fixtures/concern/some_concern.rb
new file mode 100644
index 0000000000..87f660a81e
--- /dev/null
+++ b/activesupport/test/fixtures/concern/some_concern.rb
@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+require "active_support/concern"
+
+module SomeConcern
+  extend ActiveSupport::Concern
+
+  included do
+    # shouldn't raise when module is loaded more than once
+  end
+end