* `request_parameters` [is actually POST](https://github.com/rails/rails/blob/3a428f38b2f9a1e995070a4a049645b622c7094a/actionpack/lib/action_dispatch/http/request.rb#L286)
* POST in rack [will parse multipart posts](https://github.com/rack/rack/blob/8dc31fec37f6f53a5f0f8e24274da9035abd92b2/lib/rack/request.rb#L211)
* The multipart parser [will raise an EOFerror on bad data](https://github.com/rack/rack/blob/8dc31fec37f6f53a5f0f8e24274da9035abd92b2/lib/rack/multipart/parser.rb#L81)

This code always had the danger of raising an EOF error.  Basically the same issue as above.