Serialization issues with nested records

[mariussoutier]

Hello,

as described before on the mailing list, I'm experiencing serialization issues when accessing Avro nested records from Scalding's Typed API. It usually happens in joins, but can easily be reproduced by using .forceToDisk.

I have set up an example project here:
https://github.com/mariussoutier/avro-example/tree/scalding-avro-issue

The crash can be forced this way:
https://github.com/mariussoutier/avro-example/blob/scalding-avro-issue/src/main/scala/jobs/TrendingTagsJob.scala#L22

You can simply generate some tweets and run it locally as described in the README.