The new diff logic was too aggressive at hiding unrelated changed files.
As it only considered content modifications, files which were renamed
without modifying the content were considered as not being changed.
Added/modified/deleted binary files were affected as well because
content modifications aren't computed for them.
To fix this issue, the file context is considered in addition to
(optional) content modifications when determining which changed files
can be safely ignored. This also requires some special handling in
the diff logic for changed files without content modifications.
Change-Id: I708c12bd75e044f97949e9e9fe836b99fbca753a
e54d1c3a5f