Report: Fix JinjaView deepcopy

Previously, JinjaView used the default implementation of deepcopy.
Unfortunately, this meant that attempting to stringify the same model
with an attached JinjaView twice would fail, since Jinja's Template
class fails to deepcopy.

Now, JinjaView has an explicit __deepcopy__ method.

Change-Id: Id040255138ecd48acd942d0d8ef75ed643e15403
Merge "Report: Fix JinjaView deepcopy"