Home rails 4.2 upgrade broke json rendering
 I tried upgrading my rails app from rails 4.1.0 => 4.2.7 but found that it broke my JSON views. In particular, ActiveRecord objects no longer render correctly. For instance: Model.first.to_json in rails console now produces "#\u003cModel:0x007f9208c904e0\u003e", rather than valid JSON as before. Model.first.as_json works correctly, but for some reason, it seems to_json is calling to_s instead. I tried overriding the ActiveSupport encoder but it didn't help, and am pretty stumped. Any ideas? (UPDATE: I also noticed Time.now.utc.to_json changed from 2017-12-07T19:38:47Z => 2017-12-07 19:37:55 UTC, the latter being == time.as_json and the former == time.to_s)