connection specification will deep copy the config

activerecord/lib/active_record/connection_adapters/connection_specification.rb

@@ -7,6 +7,10 @@ def initialize(config, adapter_method)
         @config, @adapter_method = config, adapter_method
       end
 
+      def initialize_dup(original)
+        @config = original.config.dup
+      end
+
       ##
       # Builds a ConnectionSpecification from user input
       class Resolver # :nodoc:

activerecord/test/cases/connection_adapters/connection_specification_test.rb

+require "cases/helper"
+
+module ActiveRecord
+  module ConnectionAdapters
+    class ConnectionSpecificationTest < ActiveRecord::TestCase
+      def test_dup_deep_copy_config
+        spec = ConnectionSpecification.new({ :a => :b }, "bar")
+        assert_not_equal(spec.config.object_id, spec.dup.config.object_id)
+      end
+    end
+  end
+end