buster test case for forms and response transformers

Next try.  Sorry for the delay, I accidentally sent a pull request to my own master branch.  Also sorry about the whitespace edits; if you want me to, I can send you a third pull request that doesn't do that.

I also have a third branch that contains what I think should fix the new test case, but doesn't.  Not sure which is broken: the test case or the fix.  Please let me know if you would like me to elaborate.

cheers,
matthias