checking in the abstractions for valid type checking:
Merge pull request #9204 from ranjaykrishna/col-prob

schema dumper tests now conducted by ActiveRecord::Base.Connection
Avoid to_sym calls
Don't call after_commit when creating through an association and save fails, fixes #5802
Merge pull request #9115 from bensie/issue_5802

Don't call after_commit when creating through an association and save fails, fixes #5802