This is services release fixing one bug relatated to 'Portable' assemblies.
'Portable' assemblies cannot be loaded from memory, they need to be saved to hard drive first, otherwise their 'fake' references will not be resolved properly (silly 'Could not find System.Core 220.127.116.11').
Additionally they caused some assemblies to be loaded twice with different code base so theretically identical type were not recognized as such (MyInterface was provided while MyInterface was expected).
Have to admit that recognition of 'Portable' assemblies is still a little mystery for me, so it gets too eager to mark some assemblies as 'Portable'. It does no harm, but it just slows down loading sometimes (as I said, they need to be saved to disk first).