Strange console output: Rails 3.2.3 + Ruby 1.9.3-p125

I'm getting strange results in the rails console after updating to
ruby 1.9.3-p125.

1.9.3p125 :005 > y User.find(10)
  User Load (0.1ms) SELECT "users".* FROM "users" WHERE "users"."id"
= ? LIMIT 1 [["id", 10]]
--- !ruby/object:User
attributes:
  !binary "aWQ=": 10
  !binary "Zmlyc3RfbmFtZQ==": Jane
  !binary "bGFzdF9uYW1l": Doe
  !binary "ZW1haWw=": jane.doe@somewhere.com
  !binary "Y3JlYXRlZF9hdA==": 2012-04-13 03:07:46.259341000 Z
  !binary "dXBkYXRlZF9hdA==": 2012-04-13 03:07:46.259341000 Z
=> nil
1.9.3p125 :006 >

Ruby was installed with RVM and I noticed it updated yaml-0.1.4 at
that time. Maybe an utf-8 encoding issue.

Expected? Known problem? Things to try? Ask the RoR Core group? Log an
issue in github?

If I wasn’t clear, ruby 1.9.2 outputs the column names in yaml format, like…

“id”: 10

…where ruby 1.9.3 outputs…

!binary “aWQ=”: 10