Add extra security checks for Headers #229
This adds a sort of seatbelt that makes sure that applications using WebOb are less likely to be vulnerable to HTTP response splitting. Unfortunately due to the flexibility of WebOb it is difficult to guarantee that you can't add a header that is vulnerable, but this adds one more line of defense.
We want to provide some extra seatbelts for security reasons. HTTP Response Splitting is on the OWASP list after all. This should not cause any issues for existing applications that are well behaved, only if untrusted user input is used would this be an issue. However it is hard to argue against extra safety nets.