Comment 3 for bug 666848

I think I see the bug. I think this check in bzrlib/delta.py's _ChangeReporter.report needs to guard against paths[1] being None before calling is_inside_any:

        if self.view_files and not osutils.is_inside_any(self.view_files,
            paths[1]):
            return

So looking at that code you're right that views are part of the trigger for this bug.