Hashed lookup fails on String/DoubleByteStrings containing ÿ
There is an error in the hashing algorithm for DoubleByteStrings containing the Character with ASCII value 255 - the character ÿ. As a result, a String containing ÿ and an otherwise equal DoubleByteString do not hash to the same value. This means that in hashed collections (such as Bag and KeyValueDictionary), elements that are DoubleByteStrings containing ÿ cannot be looked up in the collection using the equivalent String, and vice versa.
Indexes do not use hashing and are not affected.