WiredTiger Crash when inserting documents in a specific order

We just started running the .NET driver's test suite against the wired tiger storage engine and ended up crashing the server. I have reproduced the problem in the shell on windows and was told it occurs on OSX as well. The order of the insertions is important. It has to be a Timestamp first followed by a Date on an indexed field. This does not happen on mmapv1 - only wired tiger.

First repro using _id:

db.foo.insert({ _id: new Timestamp() })

db.foo.insert({ _id: new Date() })

Second repro using an index:

db.foo.createIndex({x:1})

db.foo.insert({ x: new Timestamp() })

db.foo.insert({ x: new Date() })