Avoid deepcopying exception values

Since failure objects are by design meant to be
immutable we don't/shouldn't need to deepcopy
the exception value; so instead just do a shallow
copy and depend on the semantics that failure
objects are immutable to avoid any subsequent issues
here.

Change-Id: Id1f9ae04b330ab8c16ab2f7d1e877032639f1cb3
Merge "Avoid deepcopying exception values"