rails/rails — pull request #10811 by kennyj (2013-05-31 15:32:35+00:00)
Title: Migration dump UUID default functions to schema.rb. Fixes #10751.

Please see #10751 about this problem.
Maybe related to #10605.

In current implementation, UUID default functions are not dumped to db/schema.rb, because default value isn't extracted.

I think we should back port to 4-0-stable too.