Decode attributes pulled from URI.parse

The RFC indicates that username and passwords may be encoded.
http://tools.ietf.org/html/rfc2396#section-3.2.2

Found this trying to use the mysql://username:password@host:port/db and having special characters in the password which needed to be URI encoded.

activerecord/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
+*   Decode URI encoded attributes on database connection URLs.
+
+    *Shawn Veader*
+
 *   Add `find_or_create_by`, `find_or_create_by!` and
     `find_or_initialize_by` methods to `Relation`.
 
@@ -38,7 +42,7 @@
 
     *Jon Leighton*
 
-*   Fix bug with presence validation of associations. Would incorrectly add duplicated errors 
+*   Fix bug with presence validation of associations. Would incorrectly add duplicated errors
     when the association was blank. Bug introduced in 1fab518c6a75dac5773654646eb724a59741bc13.
 
     *Scott Willson*

activerecord/lib/active_record/connection_adapters/connection_specification.rb

@@ -73,6 +73,8 @@ def connection_url_to_hash(url) # :nodoc:
                    :database => config.path.sub(%r{^/},""),
                    :host     => config.host }
           spec.reject!{ |_,value| value.blank? }
+          uri_parser = URI::Parser.new
+          spec.map { |key,value| spec[key] = uri_parser.unescape(value) if value.is_a?(String) }
           if config.query
             options = Hash[config.query.split("&").map{ |pair| pair.split("=") }].symbolize_keys
             spec.merge!(options)

activerecord/test/cases/connection_specification/resolver_test.rb

@@ -36,6 +36,14 @@ def test_url_port
             :host     => "foo",
             :encoding => "utf8" }, spec)
         end
+
+        def test_encoded_password
+          skip "only if mysql is available" unless defined?(MysqlAdapter)
+          password = 'am@z1ng_p@ssw0rd#!'
+          encoded_password = URI.encode_www_form_component(password)
+          spec = resolve "mysql://foo:#{encoded_password}@localhost/bar"
+          assert_equal password, spec[:password]
+        end
       end
     end
   end